Conjugated polymers as functional hole selective layers in efficient metal halide perovskite solar cells

Abstract

Interface engineering is still an open question to be solved in the emerging field of metal halide perovskite solar cells. Although impressive advances have been already made in controlling the composition and the quality of the active layer, stability issues of complete devices are limiting yet the forefront of a future next generation of printable photovoltaics. At this point, the choice of proper charge selective layers is essential to yield perovskite solar cells with an optimal compromise between efficiency and stability. Even though diverse n-type materials displaying outstanding properties have been recently proposed, the record performances are yet limited to the use of p-type small molecule compounds with low hole mobility in their pristine form. In here, conjugated polymers widely used in the field of polymer solar cells are integrated in perovskite devices to behave as the hole selective layers. Apart from offering suitable hole mobility and energy matching with the valence band of the perovskite material to enable efficient charge extraction, their behaviour as potential functional barrier to protect the underlying perovskite film in standard n-i-p architectures is also discussed. Future work focused on developing novel alternatives based on more stable and efficient conjugated polymers might pave the way for the large scale production of perovskite solar cells.