High‐Performance Single‐Crystalline Perovskite Thin‐Film Photodetector

Abstract

The best performing modern optoelectronic devices rely on single-crystalline thin-film (SC-TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low-cost solution-based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light-emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin-film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC-TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain-bandwidth product, and a 100-photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness-optimized SC-TF with much higher mobility and longer recombination time. The results indicate that high-performance perovskite devices based on SC-TF may become competitive in modern optoelectronics.

Recent Advances in Halide Perovskite Single‐Crystal Thin Films: Fabrication Methods and Optoelectronic Applications

“…As mentioned above, the nucleation density, which is controlled by the nucleation energy barrier, plays a pivotal role in the final lateral sizes of single‐crystal thin films. Starting from this point, Yang et al reported a substrate‐surface modification strategy to adjust the nucleation energy barrier and provide the appropriate conditions for growing large‐area single‐crystal thin films. In this report, a confined space was constructed from slices of silicon and ITO glass, in which the former was subjected to hydrophobic treatment while the later received hydrophilic treatment via oxygen plasma.…”

Atomic‐Layer Deposition‐Assisted Double‐Side Interfacial Engineering for High‐Performance Flexible and Stable CsPbBr3 Perovskite Photodetectors toward Visible Light Communication Applications

“…For example, Prof. Li's group have fabricated CNT/CsPbBr 3 perovskite nanosheet/CNT PDs, showing high responsivity ( R ) of 31.3 A W ‐1 under a bias of 10 V . Yang et al reported that single crystalline perovskite PDs exhibits superior performance than its polycrystalline counterpart, with recorded photoconductive gain of 50 million . However, due to the long charge carrier diffusion length and poor carrier collection efficiency, many reported inorganic perovskite PDs with large grain‐size crystal show large dark current, limited responsivity, and slow photoresponse …”

Enhanced On–Off Ratio Photodetectors Based on Lead‐Free Cs3Bi2I9 Single Crystal Thin Films

“…To solve this obstacle, fabricating single crystal thin film (SCTF) has been proposed as an effective strategy, since it can inherit almost all the superior photoelectrical properties from bulk single crystal and more importantly possess a reduced thickness (down to several micrometers) 6–8. Profiting from the great advance achieved in SCTF fabrication method, organic–inorganic lead halide perovskite (e.g., MAPbX 3 ) SCTF has recently become a front runner in photodetector field 9–12. The photodetectors based on organic–inorganic halide perovskite deliver a glorious photoresponse typically with high photocurrent ( J ph ).…”

“…However, the devices based on the Cs 3 Bi 2 I 9 bulk crystals with a thickness of 1–2 mm exhibited a low photoresponse current thus resulted in the low on/off ratio (≈40) even under an ultra high voltage 27,29,30. As previously mentioned, the main reason can be ascribed to the low carrier collection efficiency owing to the excessive thickness, which raises huge challenges for photon‐generated carrier to transport through the thick crystals 10. In order to improve the device performance with high on–off ratio, it is essential to develop a facile controllable synthesis strategy to fabricate Cs 3 Bi 2 I 9 single crystals with reduced thickness.…”