Constructing Efficient Hole Transport Material through π‑Conjunction Extension for Perovskite Solar Cell

Abstract

Efficient hole transport and excellent film formation properties are essential for efficient hole transport materials (HTMs) in perovskite solar cells (PCSs). And, the π-conjugated system and the steric configuration of HTMs can affect charge-carrier mobility and film formation. So, it is feasible to develop efficient HTMs via optimizing the molecular configuration and enlarging the π-conjugation system. Herein, a low-cost spiro[fluorene-9,9′-xanthene] (SFX) core-based HTM, named SFX-DM-DPA, is designed and synthesized through molecular engineering of the efficient HTM SFX-DM by introducing extra 4,4′-dimethoxydiphenylamine units to enlarge the π-conjugation range and to further modulate the charge transport property. The resulting HTM demonstrates enhanced hole extraction/transport efficiency and desired film formation ability. PSCs based on SFX-DM-DPA yielded an impressive efficiency of 22.7%. These results confirmed the importance of precise structural adjustment of the π-conjugated range for developing low-cost and highly efficient HTMs