Combination of Poly(3-butylthiophene) Hole-Transporting Layer and Butylammonium Interface Passivation to Improve an Inorganic Perovskite Solar Cell

Abstract

Owing to their superior power conversion efficiencies (PCEs), all-perovskite tandem solar cells have recently attracted extensive attention, in which an inorganic CsPbI2Br perovskite with a wide band gap is configurated as the front photovoltaic cell. A dopant-free poly(3-butylthiophene) is an effective hole-extracting and -transporting material coated on the inorganic perovskite layer, compared with conventional poly(3-hexyl- and -octyl-thiophene)s. In addition, surface passivation of the perovskite layer using alkyl ammonium bromide, especially butyl-one, further improves the PCE, including its durability. Herein, we discussed the matching of the alkyl chain lengths for poly(3-alkylthiophene) and of the alkyl ammonium salt at the interface of the hole-extracting and passivated perovskite layers.