Photodoping in Wide‐Bandgap Perovskite Solar Cells With MXenes
Angelica Simbula, Antonio Agresti, Sara Pescetelli, Sofia Sechi, Nicola Sestu, Francesco Mattana, Federico Pitzalis, Riccardo Pau, David Dell'Angelo, Alessio Filippetti, Alessandro Mattoni, Anna Pazniak, Daniela Marongiu, Valeria Demontis, Francesco Quochi, Michele Saba, Andrea Mura, Giovanni BongiovanniABSTRACT
The defect tolerance of metal halide perovskites endows them with ambipolar transport and outstanding optoelectronic properties, yet it simultaneously inhibits intentional, controlled doping that is essential for directional charge flow in advanced optoelectronic devices. The limited strategies available to tune the electron–hole balance typically involve deep defect states and associated non‐radiative recombination that degrades the open‐circuit voltage of solar cells. Here, we incorporate chlorine‐terminate MXenes (Ti 3 C 2 Cl 2 ) into wide‐bandgap perovskite solar cells to exploit bimolecular recombination and engineer photodoping mechanisms, without sacrificing solar cell performance. In fact, compared to reference cells, MXene‐modified devices show simultaneous improvements of V OC , J SC , and fill factor, resulting in a 10% power conversion efficiency enhancement up to 18%. Ultrafast optical spectroscopy, through joint time‐resolved photoluminescence and transient absorption, quantifies the imbalance between electron and hole populations under illumination. Density functional theory calculations indicate that perovskite–MXene heterojunctions create trap states for hole capture, resulting in a prolonged lifetime of free electrons because of the generalized mass‐action law. This work demonstrates photodoping in perovskites through the use of MXenes and opens a promising pathway for directional transport, with implications not only for solar cell performance, but also for novel optoelectronic applications requiring intentional doping.