Insights into the hybrid evaporation-spin coating method: process optimization and consequences for wide band gap perovskite solar cells

Abstract

The hybrid two-step (evaporation-spin coating) fabrication method demonstrates substantial promise for achieving conformal perovskite growth on highly textured surfaces, such as industrially textured silicon heterojunction (SHJ) substrates with pyramidal features exceeding 1 μm. However, the presence of numerous process control parameters complicates the determination of optimal synthesis conditions. In this study, we employ a central composite design (CCD) based on response surface methodology (RSM) to systematically design and optimize the fabrication process. Analysis of variance (ANOVA) identifies that substrate temperature during the evaporation step as a critical parameter governing device performance. We further explore the evaporation and perovskite formation kinetics to elucidate the impact of substrate temperature on film morphology and quality. Under optimized conditions, a conformal perovskite growth on the textured surfaces is successfully realized. Wide band gap (1.68 eV) perovskite solar cells (PSCs) fabricated via this approach exhibited achieve a power conversion efficiency (PCE) of 18.63% in the absence of additional treatments and 19.24% with phenylethyl ammonium iodide (PEAI) vapor passivation.