Correlation between Photoluminescence Features and Enhanced Performance in Formamidinium Lead Triiodide Quantum Dot Solar Cells by Replacement of Octadecene

In this study, an innovative approach is developed for fabricating formamidinium lead triiodide (FAPbI₃) quantum dots (QDs) by substitution of octadecene (ODE). The results showcase the formation of superior-quality FAPbI₃ QD films, boasting enhanced photoluminescence (PL) and transport properties. Specifically, ODE has been replaced with octene (OCE), a shorter linear alpha olefin. Comparisons are drawn between the novel synthesis method and the conventional ODE-based QD films, scrutinizing their optical properties and applicability in QD solar cells. The outcomes highlight distinctions in temperature-dependent PL emission characteristics, revealing an unprecedented absolute PL QY of up to 84%, a notable improvement from the 70% achieved with ODE, along with enhanced transport properties. Furthermore, the performance of both systems in QD solar cells is evaluated for two values of layer thickness, 100 and 200 nm, to investigate the transport properties at the device level. The results exhibit a remarkable improvement from 200% to 150% in average power conversion efficiency (PCE) and consistently higher values for open-circuit voltage and short-circuit current density for the OCE-based solar cell compared to an ODE-based counterpart for both thickness values, reaching a striking 6.7% PCE for the best-performing device despite the nonideal conditions.