Morphology‐Dependent Electron Transport in TiO 2 ‐Based Electron Transport Layers for Perovskite Solar Cells

ABSTRACT Perovskite solar cells (PSCs) have rapidly emerged as promising photovoltaic technologies owing to their high power conversion efficiencies and cost‐effective fabrication processes. The performance of PSCs is strongly governed by the structural and electronic characteristics of the electron transport layer (ETL), which plays a key role in charge extraction and interfacial recombination control. In this work, a systematic investigation of TiO 2 ‐based ETLs with different morphologies—powder, nanoparticles, and nanowires—is carried out to evaluate their influence on the photovoltaic performance of CH 3 NH 3 PbI 3 perovskite solar cells. TiO 2 nanowires were synthesized via a hydrothermal route, while nanoparticle‐based ETLs were prepared through solution processing. Planar PSC devices were fabricated and characterized under standard AM 1.5G one‐sun illumination. The results demonstrate that PSCs incorporating TiO 2 nanowire ETLs exhibit significantly enhanced photovoltaic performance compared with nanoparticle and powder counterparts, achieving an open‐circuit voltage of 0.92 V, a short‐circuit current density of 6.90 mA cm − 2 , a fill factor of 0.79, and a maximum power conversion efficiency of 5.08%. Structural and morphological analyses reveal that the one‐dimensional nanowire architecture promotes more efficient electron transport and suppresses charge recombination at the ETL/perovskite interface. Furthermore, diode parameters extracted using the Lambert W‐function model confirm improved electrical behavior and device stability for nanowire‐based cells. These findings highlight the critical role of ETL morphology in governing charge transport dynamics and demonstrate that TiO 2 nanowire architectures represent an effective strategy for improving the performance of perovskite solar cells.