Improving photovoltaic performance of p-i-n perovskite solar cells through FeCl₃ doping in the hole transport layer

Abstract Enhancing charge transport layers is a key approach for improving the photovoltaic performance of perovskite solar cells (PSCs). Doping the hole transport layer (HTL) has emerged as a highly effective method for achieving efficient charge transfer between charge-selective and photoactive layers. In this study, FeCl 3 , a p-type dopant, was introduced into Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) to improve the charge transfer properties of the HTL in p-i-n type PSCs. The incorporation of FeCl 3 significantly boosted the photovoltaic performance of glovebox-free fabricated MAPbI 3 -based PSCs, resulting in an approximately 15% improvement in power conversion efficiency (PCE). This improvement was primarily due to a higher short circuit current density ( J SC ) and an increased fill factor ( FF ). Morphological and structural analyses demonstrated that FeCl 3 -doped PEDOT:PSS promotes superior perovskite crystallization and the growth of larger grains. The reduction in grain boundaries and enhanced charge transfer between the perovskite layer and the HTL highlight the critical role of FeCl 3 in improving PSC performance.