Tailoring the Quantum Well Structure and Distribution of Reduced-Dimensional Perovskites for Charge Dynamics Optimization

Reduced-dimensional perovskites (RDPs) are widely used to bolster the stability of perovskite photovoltaics by forming quantum well (QW) structures and impact device performance by tuning QW width distribution. However, there is a lack of understanding about how the phase distribution affects the carrier localization and electron-phonon coupling, as well as their influences on charge dynamics. Herein, we employ a simple strategy to control the crystallization kinetics of RDP films by varying the sequence of incorporating the large organic salt, 2-thiopheneethylammonium iodide (TEAI), in the two-step fabrication method. When incorporating TEAI at the first step, the formation of the TEA-related intermediate phase promotes the preferential directional growth of RDPs with n ≥ 3. Due to the low energy disorder with the preferred energy landscape, the enhanced electron-phonon coupling in RDPs extends the charge recombination lifetime and ensures effective charge collection. The resultant inverted RDP devices achieve an efficiency of 21.0%, accompanied by enhanced operational stability.