Publications

Lead halide perovskites have attracted increasing interest for their exciting potential in diverse optoelectronic devices. However, their charge transport properties remain elusive, plagued by the issues of excessive contact resistance and large hysteresis in ambient conditions. Here we report a van der Waals integration approach for creating high-performance contacts on monocrystalline halide perovskite thin films with minimum interfacial damage and an atomically clean interface. Compared to the deposited contacts, our van der Waals contacts exhibit two to three orders of magnitude lower contact resistance, enabling systematic transport studies in a wide temperature range. We report a Hall mobility exceeding 2,000 cm2 V–1 s–1 at around 80 K, an ultralow bimolecular recombination coefficient of 3.5 × 10–15 cm3 s–1 and a photocurrent gain >106 in the perovskite thin films. Furthermore, magnetotransport studies reveal a quantum-interference-induced weak localization behaviour with a phase coherence length up to 49 nm at 3.5 K. Our results lay the foundation for exploring new physics in this class of ‘soft-lattice’ materials. This study extends the vdW integration approach for damage-free integration of metal contacts on delicate halide perovskite thin films with atomically clean interface, realizing high performance vdW contacts with 2-3 orders of magnitude lower contact resistance (than that of the deposited contacts), for the first time to allow systematic electrical transport studies of halide perovskite down to cryogenic temperatures, revealing many critical insights on the fundamental transport characteristics including an ultralow biomolecular recombination rate and a highest Hall mobility exceeding 2,000 cm2/Vs. The damage-free integration of high-quality contacts marks an important step towards unraveling the complex transport properties of halide perovskites and defines the technical foundation for exploring new physics in this unique class of “soft-lattice” materials.