Circumventing UV light induced nano-morphology disorder to achieve long lifetime PTB7-Th:PCBM based solar cells
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ProjectPRODUCCION FIABLE DE ENERGIA LIMPIA MEDIANTE LA RECOLECCION DE LUZ SOLAR USANDO UNA RED DE FIBRAS (MINECO-MAT2014-52985-R)
Large area flexible electronics rely on organic or hybrid materials prone to degradation limiting the device lifetime. For many years, photo-oxidation has been thought to be one of the major degradation pathways. However, intense illumination may lead to a burn-in or a rapid decrease in performance for devices completely isolated from corrosive elements as oxygen or moisture. The experimental studies we present in here indicate that a plausible triggering for the burn-in is a spin flip after a UV photon absorption leading to the accumulation of electrostatic potential energy that initiates a rapid destruction of the nano-morpholgy in the fullerene phase of a polymer cell. To circumvent this and achieve highly stable and efficient devices, we induce a robust nano-crystalline ordering in the PCBM phase prior to UV illumination. In that event, PTB7-Th:PC71BM cells are shown to exhibit T80 lifetimes larger than 1.6 years under a continuous UV-filtered 1-sun illumination, equivalent to 7 years for sunlight harvesting at optimal orientation and 10 years for vertical applications.
CitationLiu, Q. [et al.]. Circumventing UV light induced nano-morphology disorder to achieve long lifetime PTB7-Th:PCBM based solar cells. "Advanced Energy Materials", 17 Juliol 2017.