Defect-Healed Perovskite Quantum Dots for Optoelectronic Applications in Indoor Photovoltaics and
Seon Joong Kim1, Junhyeok Park2, Byung Ku Jung2
1School of Electrical Engineering, Korea University, Seoul, Republic of Korea.
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Metal-halide perovskite (Pe) quantum dots (QDs) offer composition- and size-tunable bandgaps, high absorption coefficients, defect tolerance, and solution processability, rendering them compelling photoactive materials for thin film photovoltaics (PVs). Nevertheless, their synthesis and purification introduce traps that lower device performance and reduce stability. In this study, a dispersion-phase defect-healing strategy was developed that combines a low loading of lead sulfide (PbS) QDs with PeQDs. In the mixed dispersion, S2- coordinates with the exposed Pb on the PeQDs, while Pb2+ and Br- from the Br-doped PbS QDs are incorporated into the PeQDs in a manner consistent with vacancy-related defect passivation. This stabilizes the Pe phase, reduces trap density, and enhances carrier mobility. PeQD PVs achieve a power conversion efficiency (PCE) of 15.1% ± 0.2% under 1-sun illumination and deliver an output power density of 118.8 ± 1.5 µW cm-2 (PCE = 40.9% ± 0.5%) under light-emitting diode illumination at 6500 K and 1000 lx. PeQD PVs were applied as photodetectors for noncontact reflection-mode photoplethysmography under low-intensity reflected light. Unencapsulated devices retained >80% of their initial PCE after 1000 h in ambient air at 30%-40% relative humidity. This approach provides a scalable route for defect control in PeQDs for high-performance, durable PVs.
