The Multifunctional Role of Thiourea in Enhancing Crystallinity and Charge Carrier Dynamics in Perovskite Solar Cells
Abstract
This study systematically investigates the role of thiourea (TU) as an additive in optimizing the performance of (FAPbI3)0.85(MAPbBr3)0.15 perovskite solar cells (PSCs). Using controlled fabrication in an inert glove-box environment, we examined how varying TU concentrations (0–0.15 mM) influences film morphology, crystallinity, and photovoltaic performance. More specifically, X-ray diffraction (XRD), UV-Vis and photoluminescence (PL) spectroscopy, and scanning electron microscopy (SEM) measurements revealed that 0.1 mM TU significantly enhances film quality, producing larger, more uniform grains (∼2 μm) with improved crystallographic orientation along the (001) and (002) planes with less pinholes. The champion solar cell devices achieved a PCE of 19% with Voc = 1.11 V, Jsc = 23.5 mA/cm2, and FF = 73%, representing a significant improvement over the control device (PCE of 15.5%). These findings offer practical guidelines for the application of morphology-advancing additives in perovskite photovoltaics and contribute to the development of more efficient and stable solar energy conversion devices.