Conjugated copolymers as doping- and annealing-free hole transport materials for highly stable and efficient p–i–n perovskite solar cells

Abstract

Significant advances in organic–inorganic halide perovskite solar cells (Pero-SCs) have been achieved in recent times. In high performance Pero-SCs, poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) is an effective polymer hole transport layer (HTL), but the requisite dopants and thermal annealing may limit its application in terms of the cost and stability of the resulting devices. Therefore, doping- and annealing-free HTLs are highly demanded for the long-term development of Pero-SCs. In the present study, we designed and synthesized three block copolymers with conjugated backbones (denoted as DTS, CDT, and DTP) and applied them as HTLs in p–i–n Pero-SCs with the configuration ITO/HTL/PSBMA/MAPbI₃(Cl)/C₆₀/BCP/Ag. These three materials require neither doping nor annealing as HTLs, and we obtained high power conversion efficiencies (PCEs) of 20.16%, 20.05%, and 17.60% for Pero-SCs based on DTS, CDT, and DTP, respectively. More importantly, the devices are quite tolerant to moisture and heat. The unencapsulated Pero-SCs retained over 94% of their initial PCE after 1500 h in air with a relative humidity of ∼20%, and over 83% of their initial PCE after 400 h at 85 °C.