In Situ Back-Contact Passivation Improves Photovoltage and Fill Factor in Perovskite Solar Cells.

Tan, Furui; Tan, Hairen; Saidaminov, Makhsud I; Wei, Mingyang; Liu, Mengxia; Mei, Anyi; Li, Peicheng; Zhang, Bowen et al. · Adv Mater · 2019

basic_science · Level V

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Abstract

Organic-inorganic hybrid perovskite solar cells (PSCs) have seen a rapid rise in power conversion efficiencies in recent years; however, they still suffer from interfacial recombination and charge extraction losses at interfaces between the perovskite absorber and the charge-transport layers. Here, in situ back-contact passivation (BCP) that reduces interfacial and extraction losses between the perovskite absorber and the hole transport layer (HTL) is reported. A thin layer of nondoped semiconducting polymer at the perovskite/HTL interface is introduced and it is shown that the use of the semiconductor polymer permits-in contrast with previously studied insulator-based passivants-the use of a relatively thick passivating layer. It is shown that a flat-band alignment between the perovskite and polymer passivation layers achieves a high photovoltage and fill factor: the resultant BCP enables a photovoltage of 1.15 V and a fill factor of 83% in 1.53 eV bandgap PSCs, leading to an efficiency of 21.6% in planar solar cells.