Improving Photodetector Performance Through Halide Vacancy Passivation in Perovskite Quantum Dots
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Improving photocurrent efficiency in perovskite quantum dot (PQD) photodiodes is a rapidly evolving research area in optoelectronics. PQDs have garnered significant attention due to their exceptional optoelectronic properties, including high absorption coefficients, tunable bandgaps, and ease of solution processing. These characteristics make them promising candidates for next-generation photodetectors, which are critical components in applications ranging from imaging sensors to optical communication systems. Enhancing photocurrent efficiency in PQD photodiodes is particularly crucial as it directly impacts the performance and commercial viability of photodetectors. However, perovskite materials suffer from low stability against oxygen and moisture, making it urgent to improve this aspect. One of the key defects contributing to efficiency degradation in perovskite photodetectors is halide vacancies. In CsPbI3 perovskites, the hybridization of iodide and lead orbitals directly influences the bandgap. When halide vacancies are present, shallow trap sites form near the bandgap of the perovskite, leading to a decrease in the photoluminescence quantum yield (PLQY) and charge transport ability of the PQDs, ultimately reducing the efficiency of PQD photodetectors. Therefore, the introduction of ligands that can passivate halide vacancies in PQDs is necessary. We introduced 1,3-Bis(diphenylphosphino)propane (DPPP) to induce halide vacancy passivation in PQDs. The lone pair electrons on the phosphorus atoms in the DPPP head group act as electron donors to Pb2+, leading to enhanced PLQY, reduced ion migration, and improved photodetector efficiency.