Fused Dithienoheterocycle‐Based Hole‐Transporting Materials for Efficient Perovskite Solar Cells

The development of efficient and stable hole‐transporting materials (HTMs) is critical for advancing perovskite solar cell (PSC) technology. This study presents two novel HTMs, LK‐1 and LK‐2 , based on fused dithienoheterocycle derivatives, namely, dithieno[3,2‐ f :2′,3′‐ h ]quinoxaline (DTQu) and dithieno[3,2‐ a :2′,3′‐ c ]phenazine (DTPh), designed for PSCs. These donor–acceptor–donor (D–A–D) structured HTMs exhibit planar, rigid cores that enhance π–π stacking, improving hole mobility and stability. LK‐1 and LK‐2 were synthesized and characterized for their optical, electrochemical, and thermal properties. PSCs with LK‐1 achieved a power conversion efficiency (PCE) of 18.16%, whereas LK‐2 reached 19.40%, outperforming LK‐1 due to smoother film properties and reduced recombination. Both HTMs showed high thermal stability and suitable energy alignment with the perovskite layer. LK‐2 ‐based PSCs enhanced hydrophobicity and film morphology further suggest its potential for stable, efficient PSCs, advancing the development of robust organic HTMs.