Experimental and Simulated Analysis of Polymer Hole Transport Layers and the Electrical and Optical Effects on Perovskite Solar Cells

This study presents a systematic analysis of the impact of polymer hole transport layers (HTLs) in inverted MAPbI3 perovskite solar cells (PSCs). Devices were fully fabricated under regular atmospheric conditions (≈40% humidity) and low temperature (100 °C) by using Field's Metal (FM) as an alternative top electrode. The widely known π-conjugated polymers P3HT, PTB7-Th, PBDB-T, and MEH-PPV were used as HTLs, and all of them show suitable energy alignment to MAPbI3, offering good moisture stability, solution processability, low cost, and attractiveness for large area and flexible PSCs. Morphological and structural characterization of MAPbI3 via AFM, SEM, and XRD revealed consistent crystallinity, with MEH-PPV promoting a slightly larger grain size and surface modification. Current density-voltage (J-V) characteristics showed that MEH-PPV-based PSCs achieved an enhanced open-circuit voltage (Voc ≈1.07 V) and fill factor (FF ≈75%), along with reduced hysteresis, while impedance spectroscopy (IS) confirmed enhanced charge extraction and lower ohmic losses. Simulations of external quantum efficiency (EQE) revealed that MEH-PPV reduces front-interface optical losses by ≈32% and charge recombination losses at the front and rear MAPbI3 interfaces by ≈33% and ≈75%, respectively, in comparison to P3HT.