IREC - Catalonia Institute for Energy Research
http://hdl.handle.net/2117/77490
2024-03-19T13:28:40ZSmall atom doping: a synergistic strategy to reduce SnZn recombination center concentration in Cu2ZnSnSe4
http://hdl.handle.net/2117/379278
Small atom doping: a synergistic strategy to reduce SnZn recombination center concentration in Cu2ZnSnSe4
Jiménez Arguijo, Alex; Navarro Güell, Alejandro; Sánchez González, Yudania; Malerba, Claudia; Giraldo Muñoz, Sergio; Saucedo Silva, Edgardo Ademar
Kesterite Cu2ZnSnS x Se4-x (CZTSSe) is among the most promising inorganic Earth-abundant thin-film photovoltaic technologies, although currently, the larger voltage deficit compared with more mature chalcogenide technologies is hampering solar-to-electricity conversion efficiency progress in these materials. Most of the latest reports agree on the CZTSSe defect structure as the main limitation for the open-circuit voltage. Small atom doping is suggested as an interesting strategy to reduce the concentration of defects without affecting secondary phase formation. Herein, an innovative approach based on the introduction of LiAlH4 and its further decomposition during the selenization process of CZTSe precursors, as a pathway for hydrogen and lithium/alkali transient doping, is explored. This process shows a strong beneficial influence on the crystal growth and solar cell device performance, especially with a significant improvement in V oc and fill factor. A reduction of nonradiative recombination and a remarkable fourfold increase in the carrier lifetime correlating with the reduction of the open-circuit voltage (V oc) deficit below 330¿mV is demonstrated. A mechanism on how small atoms (Li and H) interact to reduce the concentration of SnZn recombination centers while keeping doping relatively unchanged is proposed, opening fundamental perspectives for the simple and universal transient doping of thin-film chalcogenide compounds.
2022-12-22T13:41:49ZJiménez Arguijo, AlexNavarro Güell, AlejandroSánchez González, YudaniaMalerba, ClaudiaGiraldo Muñoz, SergioSaucedo Silva, Edgardo AdemarKesterite Cu2ZnSnS x Se4-x (CZTSSe) is among the most promising inorganic Earth-abundant thin-film photovoltaic technologies, although currently, the larger voltage deficit compared with more mature chalcogenide technologies is hampering solar-to-electricity conversion efficiency progress in these materials. Most of the latest reports agree on the CZTSSe defect structure as the main limitation for the open-circuit voltage. Small atom doping is suggested as an interesting strategy to reduce the concentration of defects without affecting secondary phase formation. Herein, an innovative approach based on the introduction of LiAlH4 and its further decomposition during the selenization process of CZTSe precursors, as a pathway for hydrogen and lithium/alkali transient doping, is explored. This process shows a strong beneficial influence on the crystal growth and solar cell device performance, especially with a significant improvement in V oc and fill factor. A reduction of nonradiative recombination and a remarkable fourfold increase in the carrier lifetime correlating with the reduction of the open-circuit voltage (V oc) deficit below 330¿mV is demonstrated. A mechanism on how small atoms (Li and H) interact to reduce the concentration of SnZn recombination centers while keeping doping relatively unchanged is proposed, opening fundamental perspectives for the simple and universal transient doping of thin-film chalcogenide compounds.Characterization of the stability of indium tin oxide and functional layers for semitransparent back-contact applications on Cu(in,Ga)Se2 solar cells
http://hdl.handle.net/2117/377534
Characterization of the stability of indium tin oxide and functional layers for semitransparent back-contact applications on Cu(in,Ga)Se2 solar cells
Fonoll Rubio, Robert; Placidi, Marcel Jose; Hoelscher, Torsten; Thomere, Angélica; Jehl Li-Kao, Zacharie; Guc, Maxim; Izquierdo Roca, Víctor; Scheer, Roland; Perez Rodriguez, Alejandro
Herein, a detailed study of the stability of different ITO-based back-contact configurations (including bare ITO contacts and contacts functionalized with nanometric Mo, MoSe2, and MoS2 layers) under the coevaporation processes developed for the synthesis of high-efficiency Cu(In,Ga)Se2 (CIGSe) solar cells is reported. The results show that bare ITO layers can be used as efficient back contacts for coevaporation process temperatures of 480¿ºC. However, higher temperatures produce an amorphous In–Se phase at the ITO surface that reduces the contacts transparency in the visible region. This is accompanied by degradation of the solar cells’ efficiency. Inclusion of a Mo functional layer leads to the formation of a MoSe2 interfacial phase during the coevaporation process, which improves the cells’ efficiency, achieving device efficiencies similar to those obtained with reference solar cells fabricated with standard Mo back contacts. Optimization of the initial Mo layer thickness improves the contact transparency, achieving contacts with an optical transparency of 50% in the visible region. This is accompanied by a relevant decrease in back reflectivity in the CIGSe devices, confirming the potential of these contact configurations for the development of semitransparent CIGSe devices with improved optical aesthetic quality without compromising the device performance.
2022-12-01T13:29:56ZFonoll Rubio, RobertPlacidi, Marcel JoseHoelscher, TorstenThomere, AngélicaJehl Li-Kao, ZacharieGuc, MaximIzquierdo Roca, VíctorScheer, RolandPerez Rodriguez, AlejandroHerein, a detailed study of the stability of different ITO-based back-contact configurations (including bare ITO contacts and contacts functionalized with nanometric Mo, MoSe2, and MoS2 layers) under the coevaporation processes developed for the synthesis of high-efficiency Cu(In,Ga)Se2 (CIGSe) solar cells is reported. The results show that bare ITO layers can be used as efficient back contacts for coevaporation process temperatures of 480¿ºC. However, higher temperatures produce an amorphous In–Se phase at the ITO surface that reduces the contacts transparency in the visible region. This is accompanied by degradation of the solar cells’ efficiency. Inclusion of a Mo functional layer leads to the formation of a MoSe2 interfacial phase during the coevaporation process, which improves the cells’ efficiency, achieving device efficiencies similar to those obtained with reference solar cells fabricated with standard Mo back contacts. Optimization of the initial Mo layer thickness improves the contact transparency, achieving contacts with an optical transparency of 50% in the visible region. This is accompanied by a relevant decrease in back reflectivity in the CIGSe devices, confirming the potential of these contact configurations for the development of semitransparent CIGSe devices with improved optical aesthetic quality without compromising the device performance.Electric vehicle battery health expected at end of life in the upcoming years based on UK data
http://hdl.handle.net/2117/375610
Electric vehicle battery health expected at end of life in the upcoming years based on UK data
Canals Casals, Lluc; Etxandi Santolaya, Maite; Bibiloni Mulet, Pere Antoni; Corchero García, Cristina; Trilla Romero, Lluís
Second-life businesses from Electric Vehicle (EV) batteries are gaining attention considering that these batteries are deemed as inappropriate for transport purposes once they reach 80 or 70% of State of Health (SoH). However, the limited number of retired batteries and the trend in battery capacity increase hinder a realistic evaluation of second-life applications. To analyze battery reuse, a closer look at the End of Life (EoL) conditions of these batteries must be taken. This study presents a battery ageing model to estimate the SoH of EV batteries according to their age and mileage. The model is applied to the current retirement characteristics of combustion vehicles to statistically determine the expected SoH at the vehicle EoL. Results indicate that most EVs will reach EoL for reasons other than under-performance. Once retired, most EV batteries will have a SoH higher than 75% within the next 20 years, opening an interesting market for second-life businesses. However, battery reuse is an option that, considering the growing EV market, will rapidly saturate the stationary energy storage demand. Before 2040, most EV batteries will follow streams towards the circular economy, although at some point, they will have to be sent directly to recycling after the vehicular use.
2022-11-04T09:50:05ZCanals Casals, LlucEtxandi Santolaya, MaiteBibiloni Mulet, Pere AntoniCorchero García, CristinaTrilla Romero, LluísSecond-life businesses from Electric Vehicle (EV) batteries are gaining attention considering that these batteries are deemed as inappropriate for transport purposes once they reach 80 or 70% of State of Health (SoH). However, the limited number of retired batteries and the trend in battery capacity increase hinder a realistic evaluation of second-life applications. To analyze battery reuse, a closer look at the End of Life (EoL) conditions of these batteries must be taken. This study presents a battery ageing model to estimate the SoH of EV batteries according to their age and mileage. The model is applied to the current retirement characteristics of combustion vehicles to statistically determine the expected SoH at the vehicle EoL. Results indicate that most EVs will reach EoL for reasons other than under-performance. Once retired, most EV batteries will have a SoH higher than 75% within the next 20 years, opening an interesting market for second-life businesses. However, battery reuse is an option that, considering the growing EV market, will rapidly saturate the stationary energy storage demand. Before 2040, most EV batteries will follow streams towards the circular economy, although at some point, they will have to be sent directly to recycling after the vehicular use.Dual extended Kalman filter for state of charge estimation of lithium–sulfur batteries
http://hdl.handle.net/2117/375152
Dual extended Kalman filter for state of charge estimation of lithium–sulfur batteries
Trilla Romero, Lluís; Canals Casals, Lluc; Jacas Biendicho, Jordi; Paradell, Pol
Lithium-Sulfur is a promising technology for the next generation of batteries and research efforts for early-stage prototype implementation increased in recent years. For the development of a suitable Battery Management System, a state estimator is required; however, lithium-sulfur behavior presents a large non-observable region that may difficult the convergence of the state estimation algorithm leading to large errors or even instability. A dual Extended Kalman Filter is proposed to circumvent the non-observability region. This objective is achieved by combining a parameter estimation algorithm with a cell model that includes non-linear behavior such as self-discharge and cell degradation. The resulting dual Kalman filter is applied to lithium–sulfur batteries to estimate their State-of-Charge incorporating the effects of degradation, temperature, and self-discharge deviations.
2022-10-27T12:40:19ZTrilla Romero, LluísCanals Casals, LlucJacas Biendicho, JordiParadell, PolLithium-Sulfur is a promising technology for the next generation of batteries and research efforts for early-stage prototype implementation increased in recent years. For the development of a suitable Battery Management System, a state estimator is required; however, lithium-sulfur behavior presents a large non-observable region that may difficult the convergence of the state estimation algorithm leading to large errors or even instability. A dual Extended Kalman Filter is proposed to circumvent the non-observability region. This objective is achieved by combining a parameter estimation algorithm with a cell model that includes non-linear behavior such as self-discharge and cell degradation. The resulting dual Kalman filter is applied to lithium–sulfur batteries to estimate their State-of-Charge incorporating the effects of degradation, temperature, and self-discharge deviations.Procedure for Assessing the Suitability of Battery Second Life Applications after EV First Life
http://hdl.handle.net/2117/373451
Procedure for Assessing the Suitability of Battery Second Life Applications after EV First Life
Montes Torre, Tomás; Etxandi Santolaya, Maite; Eichman, Josh; Ferreira Ferreira, Victor José; Trilla Romero, Lluís; Corchero García, Cristina
Using batteries after their first life in an Electric Vehicle (EV) represents an opportunity to reduce the environmental impact and increase the economic benefits before recycling the battery. Many different second life applications have been proposed, each with multiple criteria that have to be taken into consideration when deciding the most suitable course of action. In this article, a battery assessment procedure is proposed that consolidates and expands upon the approaches in the literature, and facilitates the decision-making process for a battery after it has reached the end of its first life. The procedure is composed of three stages, including an evaluation of the state of the battery, an evaluation of the technical viability and an economic evaluation. Options for battery configurations are explored (pack direct use, stack of battery packs, module direct use, pack refurbish with modules, pack refurbish with cells). By comparing these configurations with the technical requirements for second life applications, a reader can rapidly understand the tradeoffs and practical strategies for how best to implement second life batteries for their specific application. Lastly, an economic evaluation process is developed to determine the cost of implementing various second life battery configurations and the revenue for different end use applications. An example of the battery assessment procedure is included to demonstrate how it could be carried out.
2022-09-23T12:42:46ZMontes Torre, TomásEtxandi Santolaya, MaiteEichman, JoshFerreira Ferreira, Victor JoséTrilla Romero, LluísCorchero García, CristinaUsing batteries after their first life in an Electric Vehicle (EV) represents an opportunity to reduce the environmental impact and increase the economic benefits before recycling the battery. Many different second life applications have been proposed, each with multiple criteria that have to be taken into consideration when deciding the most suitable course of action. In this article, a battery assessment procedure is proposed that consolidates and expands upon the approaches in the literature, and facilitates the decision-making process for a battery after it has reached the end of its first life. The procedure is composed of three stages, including an evaluation of the state of the battery, an evaluation of the technical viability and an economic evaluation. Options for battery configurations are explored (pack direct use, stack of battery packs, module direct use, pack refurbish with modules, pack refurbish with cells). By comparing these configurations with the technical requirements for second life applications, a reader can rapidly understand the tradeoffs and practical strategies for how best to implement second life batteries for their specific application. Lastly, an economic evaluation process is developed to determine the cost of implementing various second life battery configurations and the revenue for different end use applications. An example of the battery assessment procedure is included to demonstrate how it could be carried out.Bromine etching of kesterite thin films: perspectives in depth defect profiling and device performance improvement
http://hdl.handle.net/2117/371557
Bromine etching of kesterite thin films: perspectives in depth defect profiling and device performance improvement
Tiwari, Kunal Jogendra; Jiménez Arguijo, Alex; Giraldo, Sergio; Placidi, Marcel Jose; Calvo-Barrio, L; Fonoll Rubio, Robert; Izquierdo Roca, Víctor; Sánchez González, Yudania; Perez Rodriguez, Alejandro; Saucedo Silva, Edgardo Ademar; Jehl Li-Kao, Zacharie
Using a controlled bromine etching on kesterite absorbers, two major results are obtained. We establish the first defect depth profiling and secondary phases depth profiling of a state of the art Cu2ZnSnSe4 (CZTSe) film by using surface sensitive characterization methods (XPS and Raman spectroscopy) on successively etched samples, obtaining a direct insight on the factors hampering the performance of this class of absorber. In a second step, we demonstrate the possibility of significant improvement to the p-n interface in Cu2ZnGeSe4 (CZGSe)/CdS solar cells when a short bromine etching of the absorber is performed, with the Fill Factor improving by more than 7 points. This method offers a simple improvement pathway for state of the art kesterite devices, with a potentially broader application to thin film solar cells where the p-n interface is limiting.
2022-07-29T07:26:10ZTiwari, Kunal JogendraJiménez Arguijo, AlexGiraldo, SergioPlacidi, Marcel JoseCalvo-Barrio, LFonoll Rubio, RobertIzquierdo Roca, VíctorSánchez González, YudaniaPerez Rodriguez, AlejandroSaucedo Silva, Edgardo AdemarJehl Li-Kao, ZacharieUsing a controlled bromine etching on kesterite absorbers, two major results are obtained. We establish the first defect depth profiling and secondary phases depth profiling of a state of the art Cu2ZnSnSe4 (CZTSe) film by using surface sensitive characterization methods (XPS and Raman spectroscopy) on successively etched samples, obtaining a direct insight on the factors hampering the performance of this class of absorber. In a second step, we demonstrate the possibility of significant improvement to the p-n interface in Cu2ZnGeSe4 (CZGSe)/CdS solar cells when a short bromine etching of the absorber is performed, with the Fill Factor improving by more than 7 points. This method offers a simple improvement pathway for state of the art kesterite devices, with a potentially broader application to thin film solar cells where the p-n interface is limiting.Towards low cost and sustainable thin film thermoelectric devices based on quaternary chalcogenides
http://hdl.handle.net/2117/369719
Towards low cost and sustainable thin film thermoelectric devices based on quaternary chalcogenides
Isotta, Eleonora; Andrade Arvizu, Jacob; Syafiq, Ubaidah; Jiménez Arguijo, Alex; Navarro Güell, Alejandro; Guc, Maxim; Saucedo Silva, Edgardo Ademar; Scardi, Paolo
A major challenge in thermoelectrics (TEs) is developing devices made of sustainable, abundant, and non-toxic materials. Furthermore, the technological drive toward low sizes makes crucial the study of nano and micro configurations. In this work, thin film TE devices based on p-type Cu2+xZn1-xSnS4 and Cu2+xZn1-xSnSe4, and n-type AlyZn1-yO are fabricated by physical vapor deposition. The kesterite phases show good purity and promising TE power factor, likely enhanced by the copper–zinc order–disorder transition. Thin film generators in planar configuration are assembled by a sequential deposition of the p-type, n-type, and contact materials. The power per unit planar area reaches 153 and 279 nW cm-2 for the sulphur- and selenium-based generators, respectively. These values significantly outperform any other literature attempt based on sustainable and low-cost thin films. Furthermore, if compared with traditional TEs often made of scarce and toxic materials, these devices offer a cost reduction above 80%. This allows reaching comparable values of power density per unit material cost, representing a first real step toward the development of sustainable and non-toxic thin film TE devices. These can find applications in micro energy harvesters, microelectronics coolers, and temperature controllers for wearables, medical appliances, and sensors for the internet of things.
This is the peer reviewed version of the following article: Isotta, E. [et al.]. Towards low cost and sustainable thin film thermoelectric devices based on quaternary chalcogenides. "ADVANCED FUNCTIONAL MATERIALS", 20 Maig 2022, núm. 2202157, which has been published in final form at https://onlinelibrary.wiley.com/doi/10.1002/adfm.202202157. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
2022-07-06T11:16:57ZIsotta, EleonoraAndrade Arvizu, JacobSyafiq, UbaidahJiménez Arguijo, AlexNavarro Güell, AlejandroGuc, MaximSaucedo Silva, Edgardo AdemarScardi, PaoloA major challenge in thermoelectrics (TEs) is developing devices made of sustainable, abundant, and non-toxic materials. Furthermore, the technological drive toward low sizes makes crucial the study of nano and micro configurations. In this work, thin film TE devices based on p-type Cu2+xZn1-xSnS4 and Cu2+xZn1-xSnSe4, and n-type AlyZn1-yO are fabricated by physical vapor deposition. The kesterite phases show good purity and promising TE power factor, likely enhanced by the copper–zinc order–disorder transition. Thin film generators in planar configuration are assembled by a sequential deposition of the p-type, n-type, and contact materials. The power per unit planar area reaches 153 and 279 nW cm-2 for the sulphur- and selenium-based generators, respectively. These values significantly outperform any other literature attempt based on sustainable and low-cost thin films. Furthermore, if compared with traditional TEs often made of scarce and toxic materials, these devices offer a cost reduction above 80%. This allows reaching comparable values of power density per unit material cost, representing a first real step toward the development of sustainable and non-toxic thin film TE devices. These can find applications in micro energy harvesters, microelectronics coolers, and temperature controllers for wearables, medical appliances, and sensors for the internet of things.Combining 2D organic and 1D inorganic nanoblocks to develop free-standing hybrid nanomembranes for conformable biosensors
http://hdl.handle.net/2117/369050
Combining 2D organic and 1D inorganic nanoblocks to develop free-standing hybrid nanomembranes for conformable biosensors
García Torres, José Manuel; Sylla, Dioulde Huguette; Lanzalaco, Sonia; Ginebra Molins, Maria Pau; Alemán Llansó, Carlos
We report a simple approach to fabricate free-standing perforated 2D nanomembranes hosting well-ordered 1D metallic nanostructures to obtain hybrid materials with nanostructured surfaces for fexible electronics. Nanomembranes are formed by alternatively depositing perforated poly(lactic acid) (PLA) and poly(3,4-ethylenedioxythiophene) layers. Copper metallic nanowires (NWs) were incorporated into the nanoperforations of the top PLA layer by electrodeposition and further coated with silver via a transmetallation reaction. The combination of 2D polymeric nanomembranes and aligned 1D metallic NWs allows merging the fexibility and conformability of the ultrathin soft polymeric nanomembranes with the good electrical properties of metals for biointegrated electronic devices. Thus, we were able to tailor the nanomembrane surface chemistry as it was corroborated by SEM, EDX, XPS, CV, EIS and contact angle. The obtained hybrid nanomembranes were fexible and conformable showing sensing capacity towards H2O2 with good linear concentration range (0.35–10 mM), sensitivity (120 µA cm-2 mM-1) and limit of detection (7 µm). Moreover, the membranes showed good stability, reproducibility and selectivity towards H2O2
2022-06-23T10:20:30ZGarcía Torres, José ManuelSylla, Dioulde HuguetteLanzalaco, SoniaGinebra Molins, Maria PauAlemán Llansó, CarlosWe report a simple approach to fabricate free-standing perforated 2D nanomembranes hosting well-ordered 1D metallic nanostructures to obtain hybrid materials with nanostructured surfaces for fexible electronics. Nanomembranes are formed by alternatively depositing perforated poly(lactic acid) (PLA) and poly(3,4-ethylenedioxythiophene) layers. Copper metallic nanowires (NWs) were incorporated into the nanoperforations of the top PLA layer by electrodeposition and further coated with silver via a transmetallation reaction. The combination of 2D polymeric nanomembranes and aligned 1D metallic NWs allows merging the fexibility and conformability of the ultrathin soft polymeric nanomembranes with the good electrical properties of metals for biointegrated electronic devices. Thus, we were able to tailor the nanomembrane surface chemistry as it was corroborated by SEM, EDX, XPS, CV, EIS and contact angle. The obtained hybrid nanomembranes were fexible and conformable showing sensing capacity towards H2O2 with good linear concentration range (0.35–10 mM), sensitivity (120 µA cm-2 mM-1) and limit of detection (7 µm). Moreover, the membranes showed good stability, reproducibility and selectivity towards H2O2Controlling the anionic ratio and gradient in kesterite technology
http://hdl.handle.net/2117/366863
Controlling the anionic ratio and gradient in kesterite technology
Andrade Arvizu, Jacob; Fonoll Rubio, Robert; Izquierdo Roca, Víctor; Becerril Romero, Ignacio; Sylla, Dioulde Huguette; Vidal Fuentes, Pedro; Jehl Li-Kao, Zacharie; Thomere, Angélica; Giraldo, Sergio; Tiwari, Kunal Jogendra; Resalati, Shahaboddin; Guc, Maxim; Placidi, Marcel Jose
Accurate anionic control during the formation of chalcogenide solid solutions is fundamental for tuning the physicochemical properties of this class of materials. Compositional grading is the key aspect of band gap engineering and is especially valuable at the device interfaces for an optimum band alignment, for controlling interface defects and recombination and for optimizing the formation of carrier-selective contacts. However, a simple and reliable technique that allows standardizing anionic compositional profiles is currently missing for kesterites and the feasibility of achieving a compositional gradient remains a challenging task. This work aims at addressing these issues by a simple and innovative technique. It basically consists of first preparing a pure sulfide absorber with a specific thickness followed by the synthesis of a pure selenide part of complementary thickness on top of it. Specifically, the technique is applied to the synthesis of Cu2ZnSn(S,Se)4 and Cu2ZnGe(S,Se)4 kesterite absorbers, and a series of characterizations are performed to understand the anionic redistribution within the absorbers. For identical processing conditions, different Se incorporation dynamics is identified for Sn- and Ge-based kesterites, leading to a homogeneous or graded composition in depth. It is first demonstrated that for Sn-based kesterite the anionic composition can be perfectly controlled through the thicknesses ratio of the sulfide and selenide absorber parts. Then, it is demonstrated that for Ge-based kesterite an anionic (Se–S) gradient is obtained and that by adjusting the processing conditions the composition at the back side can be finely tuned. This technique represents an innovative approach that will help to improve the compositional reproducibility and determine a band gap grading strategy pathway for kesterites. Furthermore, due to its simplicity and reliability, the proposed methodology could be extended to other chalcogenide materials.
2022-05-05T11:04:39ZAndrade Arvizu, JacobFonoll Rubio, RobertIzquierdo Roca, VíctorBecerril Romero, IgnacioSylla, Dioulde HuguetteVidal Fuentes, PedroJehl Li-Kao, ZacharieThomere, AngélicaGiraldo, SergioTiwari, Kunal JogendraResalati, ShahaboddinGuc, MaximPlacidi, Marcel JoseAccurate anionic control during the formation of chalcogenide solid solutions is fundamental for tuning the physicochemical properties of this class of materials. Compositional grading is the key aspect of band gap engineering and is especially valuable at the device interfaces for an optimum band alignment, for controlling interface defects and recombination and for optimizing the formation of carrier-selective contacts. However, a simple and reliable technique that allows standardizing anionic compositional profiles is currently missing for kesterites and the feasibility of achieving a compositional gradient remains a challenging task. This work aims at addressing these issues by a simple and innovative technique. It basically consists of first preparing a pure sulfide absorber with a specific thickness followed by the synthesis of a pure selenide part of complementary thickness on top of it. Specifically, the technique is applied to the synthesis of Cu2ZnSn(S,Se)4 and Cu2ZnGe(S,Se)4 kesterite absorbers, and a series of characterizations are performed to understand the anionic redistribution within the absorbers. For identical processing conditions, different Se incorporation dynamics is identified for Sn- and Ge-based kesterites, leading to a homogeneous or graded composition in depth. It is first demonstrated that for Sn-based kesterite the anionic composition can be perfectly controlled through the thicknesses ratio of the sulfide and selenide absorber parts. Then, it is demonstrated that for Ge-based kesterite an anionic (Se–S) gradient is obtained and that by adjusting the processing conditions the composition at the back side can be finely tuned. This technique represents an innovative approach that will help to improve the compositional reproducibility and determine a band gap grading strategy pathway for kesterites. Furthermore, due to its simplicity and reliability, the proposed methodology could be extended to other chalcogenide materials.Does Sb2Se3 admit nonstoichiometric conditions? How modifying the overall se content affects the structural, optical, and optoelectronic properties of Sb2Se3 thin films
http://hdl.handle.net/2117/365192
Does Sb2Se3 admit nonstoichiometric conditions? How modifying the overall se content affects the structural, optical, and optoelectronic properties of Sb2Se3 thin films
Caño Prades, Ivan; Vidal Fuentes, Pedro; Calvo Barrio, Lorenzo; Alcobé Olle, Xavier; Giraldo, Sergio; Sánchez González, Yudania; Jehl Li-Kao, Zacharie; Placidi, Marcel Jose; Puigdollers i González, Joaquim; Izquierdo Roca, Víctor; Saucedo Silva, Edgardo Ademar; Asensi López, José Miguel
Sb2Se3 is a quasi-one-dimensional (1D) semiconductor, which has shown great promise in photovoltaics. However, its performance is currently limited by a high Voc deficit. Therefore, it is necessary to explore new strategies to minimize the formation of intrinsic defects and thus unlock the absorber’s whole potential. It has been reported that tuning the Se/Sb relative content could enable a selective control of the defects. Furthermore, recent experimental evidence has shown that moderate Se excess enhances the photovoltaic performance; however, it is not yet clear whether this excess has been incorporated into the structure. In this work, a series of Sb2Se3 thin films have been prepared imposing different nominal compositions (from Sb-rich to Se-rich) and then have been thoroughly characterized using compositional, structural, and optical analysis techniques. Hence, it is shown that Sb2Se3 does not allow an extended range of nonstoichiometric conditions. Instead, any Sb or Se excesses are compensated in the form of secondary phases. Also, a correlation has been found between operating under Se-rich conditions and an improvement in the crystalline orientation, which is likely related to the formation of a MoSe2 phase in the back interface. Finally, this study shows new utilities of Raman, X-ray diffraction, and photothermal deflection spectroscopy combination techniques to examine the structural properties of Sb2Se3, especially how well-oriented the material is.
2022-04-01T11:16:27ZCaño Prades, IvanVidal Fuentes, PedroCalvo Barrio, LorenzoAlcobé Olle, XavierGiraldo, SergioSánchez González, YudaniaJehl Li-Kao, ZachariePlacidi, Marcel JosePuigdollers i González, JoaquimIzquierdo Roca, VíctorSaucedo Silva, Edgardo AdemarAsensi López, José MiguelSb2Se3 is a quasi-one-dimensional (1D) semiconductor, which has shown great promise in photovoltaics. However, its performance is currently limited by a high Voc deficit. Therefore, it is necessary to explore new strategies to minimize the formation of intrinsic defects and thus unlock the absorber’s whole potential. It has been reported that tuning the Se/Sb relative content could enable a selective control of the defects. Furthermore, recent experimental evidence has shown that moderate Se excess enhances the photovoltaic performance; however, it is not yet clear whether this excess has been incorporated into the structure. In this work, a series of Sb2Se3 thin films have been prepared imposing different nominal compositions (from Sb-rich to Se-rich) and then have been thoroughly characterized using compositional, structural, and optical analysis techniques. Hence, it is shown that Sb2Se3 does not allow an extended range of nonstoichiometric conditions. Instead, any Sb or Se excesses are compensated in the form of secondary phases. Also, a correlation has been found between operating under Se-rich conditions and an improvement in the crystalline orientation, which is likely related to the formation of a MoSe2 phase in the back interface. Finally, this study shows new utilities of Raman, X-ray diffraction, and photothermal deflection spectroscopy combination techniques to examine the structural properties of Sb2Se3, especially how well-oriented the material is.