Modulating Charge Carrier Dynamics Through Tailored Hole Transport Layers in Perovskite Photovoltaics

ABSTRACT Hole transport layer (HTL) plays a vital role in perovskite solar cells (PSCs) and is one of the bottlenecks to further enhancements in device performance and stability. Currently the dominant choice as the hole transport material (HTM), 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD), for n‐i‐p PSCs suffer from thermal and moisture instability and high fabrication cost. In this study, we investigated three potential HTMs to replace spiro‐OMeTAD—two polymeric materials, PTAA (poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine]) and P3HT (poly(3‐hexylthiophene‐2,5‐diyl)), and a molecular material, H101 (2,5‐bis(4,4′‐bis(methoxyphenyl)aminophen‐4″‐yl)‐3,4‐ethylenedioxythiophene). Among the candidates, PTAA‐based PSCs achieved the highest efficiency of 21.01%, outperforming spiro‐OMeTAD (18.95%), P3HT (17.81%), and H101 (16.93%). Detailed charge carrier dynamics analysis revealed that PTAA's superior performance is driven by its ability to suppress non‐radiative recombination at the perovskite/HTM interface, despite a slower charge transfer process compared to other HTMs. These findings suggest that PTAA, along with P3HT and H101, provides not only comparable but potentially superior device performance while offering opportunities to enhance device stability, highlighting the potential of alternative HTMs in advancing n‐i‐p PSC technologies.