Manipulation of the Buried Interface for Robust Formamidinium‐based Sn−Pb Perovskite Solar Cells with NiO_xHole‐Transport Layers

Abstract

Low band gap tin‐lead perovskite solar cells (Sn−Pb PSCs) are expected to achieve higher efficiencies than Pb‐PSCs and regarded as key components of tandem PSCs. However, the realization of high efficiency is challenged by the instability of Sn2+ and the imperfections at the charge transfer interfaces. Here, we demonstrate an efficient ideal band gap formamidinium (FA)‐based Sn−Pb (FAPb0.5Sn0.5I3) PSC, by manipulating the buried NiOx/perovskite interface with 4‐hydroxyphenethyl ammonium halide (OH‐PEAX, X=Cl−, Br−, or I−) interlayer, which exhibits fascinating functions of reducing the surface defects of the NiOx hole transport layer (HTL), enhancing the perovskite film quality, and improving both the energy level matching and physical contact at the interface. The effects of different halide anions have been elaborated and a 20.53 % efficiency is obtained with OH‐PEABr, which is the highest one for FA‐based Sn−Pb PSCs using NiOx HTLs. Moreover, the device stability is also boosted.

Enhanced performance of perovskite solar cells via a bilateral electron-donating passivator as a molecule bridge

“…The change in electron cloud density may be attributed to the fact that the nitrogen in –NH 2 and oxygen in –OH with lone pairs of electrons can coordinate with the uncoordinated Sn 4+ in SnO 2 , which induces electron transfer from nitrogen and oxygen elements in HAL to SnO 2 . 34,35 The result of Sn 3d spectra confirms the existence of interaction between HAL and SnO 2 . From the O 1s spectra in Fig.…”

Dopant‐free NiOx Nanocrystals: A Low‐cost and Stable Hole Transport Material for Commercializing Perovskite Optoelectronics

“…Additionally, the ABABr interface modification leads to significant improvements in perovskite film morphology, crystallization, and band alignment. More recently, NiO x NCs were also introduced into the low band gap tin-lead perovskite solar cells (Sn-Pb PSCs) system by Zhou et al [67] By manipulating the buried NiO x /perovskite interface with OH-PEAX (4-hydroxyphenethyl ammonium halide, X = Cl À , Br À , or I À ) interlayer, the film quality of Sn-Pb based perovskite has been improved, resulting in the reducing of the surface defects and the improving of the energy matching. Benefitting from these, a PCE of 20.53 % is acquired for Sn-Pb PSCs, which is the highest PCE of Sn-Pb PSCs based on NiO x NCs.…”

Recent Progress of Inorganic Hole‐Transport Materials for Perovskite Solar Cells†

“…Introducing the tailored molecules to the interface between the perovskite layer and HTL is a simple strategy to reduce the defects of the perovskite surface, inhibit the redox reaction at the interface, modify the optoelectronic properties of NiO x film, and adjust the morphology of perovskite. [17,51,[54][55] Yang et al [29] reported efficient PSCs based on the modified NiO x by diethanolamine (DEA) with hydroxy and amine functional groups. The DEA could strongly interact with both NiO x and perovskite by Ni‧‧‧N, and Pb‧‧‧O interactions, resulting in improved perovskite film quality.…”