Spray-Coated Colloidal Perovskite Quantum Dot Films for Highly Efficient Solar Cells

Abstract

A fully automated spray-coated technology with ultrathin-film purification is exploited for the commercial large-scale solution-based processing of colloidal inorganic perovskite CsPbI<inf>3</inf> quantum dot (QD) films toward solar cells. This process is in the air outside the glove box. To further improve the performance of QD solar cells, the short-chain ligand of phenyltrimethylammonium bromide (PTABr) with a benzene group is introduced to partially substitute for the original long-chain ligands of the colloidal QD surface (namely PTABr-CsPbI<inf>3</inf>). This process not only enhances the carrier charge mobility within the QD film due to shortening length between adjacent QDs, but also passivates the halide vacancy defects of QD by Br⁻ from PTABr. The colloidal QD solar cells show a power conversion efficiency (PCE) of 11.2% with an open voltage of 1.11 V, a short current density of 14.4 mA cm⁻², and a fill factor of 0.70. Due to the hydrophobic surface chemistry of the PTABr–CsPbI<inf>3</inf> film, the solar cell can maintain 80% of the initial PCE in ambient conditions for one month without any encapsulation. Such a low-cost and efficient spray-coating technology also offers an avenue to the film fabrication of colloidal nanocrystals for electronic devices.