A Triazine-Based Hole Transport Material for Durable Perovskite Solar Cells

Abstract

Hole-transport materials (HTMs) with suitable band alignment and simplified fabrication processes are essential to enhance the performance of perovskite solar cells (PSCs) with n–i–p structures. Although 2,2′,7,7′-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD) has been a common HTM in PSCs, its complex synthesis process and high cost hinder its commercialization. Herein, a donor–acceptor–donor (D–A–D)-type novel small-molecule HTM, 6-phenyl-1,3,5-triazine-2,4-bis[di(4-methoxyphenyl)amino]carbazole (PTBC), synthesized using low-cost materials and a highly simplified one-step process, is reported. PTBC passivates perovskite (PVK) surface defects and forms an appropriate energy band alignment with the PVK light absorption layer, enhancing the hole extraction capability. The hydrophobic nature of PTBC additionally prevents the degradation of the PVK layer caused by conventional dopants. The best PTBC-based PSC yields a power conversion efficiency (PCE) of up to 20.17%, retaining 90.96% of initial performance stored after 2568 h. This novel HTM, PTBC, is expected to pave the way for the commercialization of cost-effective and long-term stable PSCs as an alternative solution to overcome the limitations associated with Spiro-OMeTAD.