Xiaoyuan Liu1 Chen Li1

1, Southern University of Science and Technology of China, ShenZhen, , China

Herein, we report perovskite solar cells (PSCs) with the highest reported power conversion efficiency (PCE) using phthalocyanine complexes as a dopant-free hole-transport layer (HTL). As low-cost hole-transport materials, phthalocyanine complexes can provide high thermal and chemical stability with high carrier mobility. Five tetra-alkyl substituted phthalocyanine copper(II) complexes with different alkyl chain lengths were synthesized, characterized, and used as HTLs in PSCs. The effect of the alkyl side chain length on the structural and electronic properties of the HTL in PSC devices was investigated. We found that tetra-propyl-substituted copper(II) phthalocyanine (CuPrPc), which has the strongest π–π interaction and a face-on molecular orientation, deposited on perovskite by spin coating leads to higher hole mobility than the other prepared tetra-alkyl-substituted copper(II) complexes and it forms a highly hydrophobic surface that considerably enhances the stability of the perovskite layer. A highly efficient PSC device was fabricated, and a stable PCE of 17.0% was achieved. The results show that CuPrPc has potential as a hole-transport material for fabricating PSCs.