Conjugated N‐Type Diradical Semiconductor Empowers High‐Performance TiO ₂ ‐Based Perovskite Solar Cells

ABSTRACT Titanium dioxide (TiO ₂ ) plays a critical role as an electron transport layer in perovskite solar cells (PSCs). However, the efficiency of TiO ₂ ‐based PSCs lags significantly behind that of tin dioxide (SnO ₂ )‐based counterparts, primarily due to their high density of surface defects and low conductivity. In this work, we developed a novel n‐type conjugated diradical semiconductor, namely IDT‐R, which features suitable energy levels and superior electron mobility. Importantly, when deposited on TiO ₂ , IDT‐R serves a dual function: it effectively passivates surface defects while concurrently enhancing the intrinsic conductivity of TiO ₂ . This synergistic effect significantly improves electron extraction and transport at the buried interface. Consequently, the devices based on IDT‐R deliver a high power conversion efficiency (PCE) of 25.38% along with enhanced thermal stability. This work focuses on modulating the electrical properties of TiO ₂ and explores, for the first time, a n‐type diradical semiconductor toward interface engineering at the electron‐selective contact in PSCs.