Improving performance of perovskite solar cells enabled by defects passivation and carrier transport dynamics regulation via organic additive

Abstract

Defects at the grain boundaries (GBs) of perovskite film highly restrict both the efficiency and stability of perovskite solar cells (PSCs). Herein, organic small molecules of butanedioic acid (BA) and acetylenedicarboxylic acid (AA), containing two electron-donors of carbonyl (C=O) groups and different core-units, were incorporated into perovskite as additives for PSCs application. Thanks to the strong coordination interaction between C=O group and under-coordinated Pb2+, the additives can effectively passivate film defects and regulate the perovskite crystallization, yielding high-quality perovskite films with lower defect densities. More importantly, the additives can efficiently regulate the charge transport behaviors in PSCs. Benefiting from the defects passivation and the regulation of charge carrier dynamics, the BA and AA-treaded PSCs show the power conversion efficiencies of 21.52% and 20.50%, which are higher than that of the control device (19.41%). Besides, the optimal devices exhibit a remarkable enhanced long-term stability and moisture/oxygen tolerance compared to the pristine devices. Furthermore, the transient absorption spectrum reveals the mechanism of enhanced photovoltaic performances, attributing to the improvement of charge transport capability at the perovskite/Spiro-OMeTAD interfaces. This work affords a promising strategy to improve the efficiency and stability of PSCs through regulating the charge-carrier dynamic process in perovskite film.