All-Perovskite Low-Dimensional/Quantum Dot Heterojunctions for Long-Term Efficient Quantum Dot Solar Cells.

In recent years, halide perovskite quantum dot (PQD) solar cells have garnered more research interest, yet poor operational and environmental stability limit their commercialization. Herein, a robust all-perovskite low-dimensional (LD)/PQD heterojunction is proposed to address these issues. In particular, rationally designed 2D perovskite single crystals dissolved in optimized solvents are directly coated on the PQD matrix to drive spontaneous conformal LD prototype growth. Notably, this strategy features a heating-free procedure with negligible erosion characteristics. Benefiting from the well-matched energy-level alignment at the intimate heterojunction, interfacial charge extraction is synergistically promoted, while a defect-free 2D single-crystal layer suppresses humidity-induced degradation via effective encapsulation. With this engineered LD/PQD heterojunction, the optimized FAxCs1-xPbI3 PQD device delivers a champion efficiency of 17.6% (certified value of 16.98%), with 9-fold enhanced humidity stability versus that of the pure PQD analogue. This work provides a novel heterostructure construction paradigm and mechanistic guidance for improving the efficiency and environmental stability of PQD-based optoelectronic devices.