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

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