Precursor engineering for controlled self-doping and enhanced performance in MAPbCl3 single crystals

Abstract

Halide perovskites have emerged as highly promising materials for light absorption and emission, with significant potential in photovoltaics and optoelectronics. However, unintentional self-doping in solution-processed lead halide perovskite single crystals often degrades photodetector performance. In this study, we present an innovative precursor engineering approach aimed at controlling the self-doping characteristics of perovskite materials by optimizing the stoichiometry of the precursors. By precisely adjusting the PbCl₂/MACl (MA = CH₃NH₃⁺) ratio, we achieved remarkable enhancements in MAPbCl₃ single crystal performance. The crystal with a PbCl₂/MACl molar ratio of 0.85 exhibited exceptional properties, including a high resistivity (2.7 × 10⁸ Ω cm), outstanding carrier mobility (116.1 cm² V⁻¹ s⁻¹), and ultralow trap state density (9.03 × 10⁸ cm⁻³). Additionally, the fabricated MAPbCl₃ single crystal ultraviolet photodetector (vertical architecture) demonstrated a high responsivity of 105 mA W⁻¹ at 365 nm, with ultrafast response speed (rise time: 38.2 μs, fall time: 61.4 μs), surpassing all previously reported MAPbCl₃ single crystal-based devices. These results highlight the superior quality of the optimized crystals, demonstrating their potential for use in high-performance optoelectronics and advancing perovskite integration into next-generation photonic and electronic technologies.