Scalable, Template Driven Formation of Highly Crystalline Lead‐Tin Halide Perovskite Films

Abstract

Low bandgap lead‐tin halide perovskites are predicted to be candidates to maximize the performance of single junction and tandem solar cells based on metal halide perovskites. In spite of the tremendous progress in lab‐scale device efficiency, devices fabricated with scalable techniques fail to reach the same efficiencies, which hinder their potential industrialization. Herein, a method is proposed that involves a template of a 2D perovskite deposited with a scalable technique (blade coating), which is then converted in situ to form a highly crystalline 3D lead‐tin perovskite. These templated grown films are alloyed with stoichiometric ratio and are highly oriented with the (l00) planes aligning parallel to the substrate. The low surface/volume ratio of the obtained single‐crystal‐like films contributes to their enhanced stability in different environments. Finally, the converted films are demonstrated as active layer for solar cells, opening up the opportunity to develop this scalable technique for the growth of highly crystalline hybrid halide perovskites for photovoltaic devices.

The Fascinating Properties of Tin-Alloyed Halide Perovskites

“…Despite the superior quality and stability obtained, the fabrication costs and skills needed make the process rather challenging to implement in large-scale fabrication. Instead, our group has developed a scalable fabrication, which involves the initial deposition by blade-coating of a Ruddlesden–Popper SnPb perovskite as a growth template, which is then converted into FASnPbI 3 by an in situ reaction with FAI . The formed film possesses a highly preferred orientation, differing from the spin-cast films of the alloy (Figure c).…”

“…Copyright 2020, The Author(s), under exclusive licence to Springer Nature Limited. (c) Grazing-incidence wide-angle X-ray scattering (GIWAXS) patterns of spin-casted and layered (PEA 2 Sn 0.5 Pb 0.5 I 3 )-templated FASn 0.5 Pb 0.5 I 3 films from ref , submitted for publication 2021.…”

“…Instead, our group has developed a scalable fabrication, which involves the initial deposition by bladecoating of a Ruddlesden−Popper SnPb perovskite as a growth template, which is then converted into FASnPbI 3 by an in situ reaction with FAI. 61 The formed film possesses a highly preferred orientation, differing from the spin-cast films of the alloy (Figure 4c). We believe this deposition method will have an important future in the scalable growth of stable Sn-alloyed perovskites.…”

Modulating preferred crystal orientation for efficient and stable perovskite solar cells—From progress to perspectives

“…As the annealing temperature increases, the low‐number 2D phases tend to disappear, and the film shows a desirable 2D structure with the (111) plane being perpendicular to the substrates when annealed at 100°C, resulting in a PCE of 9.1% 106 . Xi et al 107 proposed an in situ conversion strategy involving a template 2D perovskite to form highly‐oriented 3D Pb‐Sn mixed perovskite. A 2D (PEA) 2 Pb 0.5 Sn 0.5 I 4 perovskite was first blade‐coated as a growth template, followed by dipping the film into the FAI/IPA solution to induce in situ cation exchange to prepare 3D FAPb 0.5 Sn 0.5 I 3 (Figure 11A).…”

“…XRD patterns of (B) layer‐template (LT) and (C) spin‐coated (SP) FAPb 0.5 Sn 0.5 I 3 films. Reproduced with permission 107 . Copyright 2021, Wiley‐VCH.…”