Multifunctional Optimization of MXene for Enhanced Comprehensive Performance of Crystal Silicon‐MXene Back‐Heterojunction Solar Cells

Abstract Enhancing the cost‐performance ratio is a fundamental objective for the advancement of the photovoltaic sector. In this context, the development of innovative solar cells that offer a straightforward device configuration but high performance is arguably the most crucial element. Herein, an undoped back‐heterojunction crystalline silicon (c‐Si) solar cell is endeavored to be crafted by simply drop‐casting a Ti 3 C 2 T x MXene ethanol colloidal solution onto the backside of an n ‐type c‐Si ( n ‐Si) wafer. Leveraging the good electrical property and stability, as well as the adjustable work function of MXene treated by europium trifluoromethanesulfonate (Eu(OTF) 3 ), the elementary Ag/ZnO/ n ‐Si/MXene/Ag solar cell delivers an impressive power conversion efficiency (PCE) of 12.5%. Moreover, the deposition of a SiO 2 passivation layer through a simple self‐developed electrochemical method increases the PCE further to 13.5% by ameliorating the interfacial contact between MXene and n ‐Si. Moreover, this unencapsulated solar cell exhibits improved stability, compared to the control device without Eu(OTF) 3 treatment and SiO 2 passivation.