Exploring Charge Transfer Dynamics in Perovskite Solar Cells Using First-Principles Methods

The potential of perovskite solar cells (PSCs) as a cost-effective, high-efficiency renewable energy source is largely hindered by their stability and performance issues.¹ The primary concerns originate from the interfaces between the perovskite and hole transport materials. In this study, we investigate these interface-related problems using cutting-edge first-principles calculations to offer a deeper understanding of charge transfer (CT) mechanisms and times in PSCs, particularly focusing on the role of perovskite chemical composition and the local interfacial environment.² Our study provides a detailed analysis of the interfaces between the spiro-MeOTAD hole transport material and two perovskite formulations: methylammonium lead iodide (MAPI) and the triple cation layered halide perovskite (LHP). We identify key chemical factors that promote favorable binding and enhance CT at these interfaces. We find that electronic interactions play a critical role in interface stability. By examining the coupling matrix elements and partial density of states, we identify specific LHP states acting as CT channels and observe a correlation between the best couplings and the localization of molecular orbitals toward the LHP surface.<br/>Our analysis offers a novel atomic-scale perspective for a comprehensive rationalization of charge transfer mechanisms and times for some of the most representative systems of current state-of-the-art PSCs, paving the route to further investigation on the effects of dopants, defects, or buffer interlayers on key processes such as interfacial charge transfer.<br/><br/>1 T. A. Chowdhury, M. A. B. Zafar, M. S.-U. Islam, M. Shahinuzzaman, M. A. Islam and M. U. Khandaker, <i>RSC Adv.</i>, 2023, <b>13</b>, 1787–1810.<br/>2 A. Pecoraro, F. Fasulo, M. Pavone and A. B. Muñoz-García, <i>Chem. Commun.</i>, 2023, <b>59</b>, 5055–5058.