# Scalable Fabrication of High‐Efficiency Thin‐Film Perovskite Solar Cells in Air via Polymer‐Mediated Synthesis of α‐FAPbI3 Microcrystals

## TL;DR

Researchers developed a scalable method to produce stable and efficient perovskite solar cells using a polymer-coated material that can be processed in air.

## Contribution

A scalable air-compatible fabrication method for high-efficiency perovskite solar cells using PPG-coated α-FAPbI3 microcrystals is introduced.

## Key findings

- PPG-coated α-FAPbI3 microcrystals retain phase purity for over six months in air.
- A laboratory-scale PSC achieved a power conversion efficiency of 26.5%.
- The method enables large-scale production with over 95% yield and enhanced film properties.

## Abstract

Formamidinium lead triiodide (FAPbI3) perovskite solar cells (PSCs) demonstrate exceptional photovoltaic performance but face critical stability challenges impeding commercialization. Herein, we integrate polypropylene glycol (PPG) into an inverse temperature crystallization process to synthesize highly stable α‐FAPbI3 microcrystals, which retain phase purity for over six months in air. Our approach enables large‐scale production (nearly 50 g) of PPG‐coated α‐FAPbI3 (target) microcrystals from low‐cost PbI2, with over 95% yield—sufficient to manufacture 23 m2 of perovskite solar modules. Redissolving the target α‐FAPbI3 microcrystals, followed by spin‐coating and annealing, yields target perovskite films with reduced defect density, minimized residual strain, and enhanced carrier transport. Mechanistic investigations reveal that colloidal species form upon the redissolution of target microcrystals which modulate the film crystallization kinetics, i.e. accelerating (100)‐oriented nucleation and growth. Employing this integrated strategy, a champion PSC with a power conversion efficiency (PCE) of 26.50% (certified 26.22%) was obtained at a laboratory scale (0.06 cm2) and 22.66% for a module with an aperture area of 28.99 cm2, together with prolonged operational stability. This work opens new avenues for the industrial‐scale fabrication of efficient and stable large‐area perovskite photovoltaics.

We report a scalable strategy using PPG‐coated α‐FAPbI3 microcrystals that may be processed in air and undergo controlled redissolution to form highly oriented, defect‐suppressed perovskite films. The PSCs derived from these films deliver a PCE of 26.5% and exhibit enhanced stability, demonstrating potential for industrial large‐scale perovskite photovoltaic manufacturing.