Room‐Temperature Crystallization of Ultralong (≈3.5 mm) CsCu₂I₃ Microbelt to Suppress Carrier Recombination for High‐Performance UV Heterojunction Photodetector

Abstract

has surpassed 25.5%, [2] and the external quantum efficiency (EQE) of perovskite LEDs has been dramatically boosted to over 20%. [3] However, there exist two main problems with organic lead halide perovskites. First, the toxicity of lead in perovskite has severely restricted its commercialization. Therefore, on the basis of inheriting the excellent performance of lead-based perovskites, it is of great significance to develop nontoxic lead-free halide perovskites for optoelectronic applications. [4] To date, a rapid development has been achieved in the past years, and a large amount of environment-friendly metal cations have been selected to replace Pb 2+ to reduce the toxicity to humans and the environment, including Sn 2+ , Cu + , Bi 3+ , Ge 2+ , and Sb 3+ . [2] Second, the instability to moisture, light and heat, which comes from the intrinsic organic cationic group, limits its practical application. [4] From the application point of view, it is required that the lead-free halide perovskite should exhibit enough stability to the disturbance from external environment. It is proved that reducing the structural dimensions of the perovskite can effectively improve its stability. [5] Consequently, low-dimensional metal halide perovskite analogues at molecular level, which demonstrate good stability and unique photophysical properties, have attracted tremendous attention in the field of optoelectronics. [6] Recently, as an ideal candidate of novel low-dimensional metal halide perovskite analogues, 1D CsCu 2 I 3 has been investigated in many aspects of photodetection field. Highly stable CsCu 2 I 3 single crystal was fabricated as facet-dependent, fast response, and broadband photodetector. [7] Oriented-structured CsCu 2 I 3 film detector achieved high-resolution X-ray imaging. [8] Solution-processed CsCu 2 I 3 nanowires were introduced to construct polarization-sensitive and flexible UV photodetector. [9] High-performance deep UV photodetector was built up based on the CsCu 2 I 3 film. [10] In addition, 1D CsCu 2 I 3 perovskite analogue also shows great potential in the field of LEDs. Highly efficient 1D CsCu 2 I 3 single crystal was emerged as the downconversion phosphors for white-LEDs. [11] Through localized 1D excitonic recombination, a high photoluminescence quantum yield (PLQY) was realized in CsCu 2 I 3 single crystal. [12] However, this typical strong excitonic recombination and short carrier Lead-free ternary copper iodide perovskite analogues demonstrate great potential in photodetector, due to their nontoxity and excellent photophysical properties. However, the fast carrier recombination limits the photoelectric conversion efficiency. Herein, a room-temperature growth strategy with the selected raw ratio is adopted to enhance carrier dynamics. The optimizedgrown CsCu 2 I 3 single crystal exhibits longer carrier lifetime of 157 ns, and its switch ratio and response time are enhanced by 20 000% and 600% compared with those of stoichiometric-grown single crystal, respectively. Furthermore, space-confined meth...

Direct growth of SnS2 nanowall photoanode for high responsivity self-powered photodetectors

“…The active materials of photodetectors with large specific surface area, high electron mobility, fast diffusion and low carrier recombination enable more light absorption and photoelectric current enhancement. 15,16 Meanwhile, the redox pairs in the electrolyte not only act as a mediator for transfer charges between electrodes but also separate electron–hole pairs.…”

Spherulitic Crystallization of CsCu2I3 for High Performance Ultraviolet Photodetectors

“…Commercial UV photodetectors utilizing silicon and photomultiplier tubes suffer from inherent limitations such as poor selectivity for visible–infrared photons and susceptibility to degradation under UV irradiation. , Wide-bandgap semiconductors with energy bandgaps greater than 3.3 eV, including GaN, SiC, SnO 2 , TiO 2 , In 2 O 3 , and ZnO, have been utilized for visible-blind UV photodetectors. − However, these materials typically necessitate demanding fabrication processes such as magnetron sputtering, pulsed laser deposition, flame spray pyrolysis, and chemical vapor deposition . As a result, there has been a growing focus on developing UV photodetectors based on solution-processed wide bandgap materials. − Recently, solution-processed ternary copper halides have emerged as promising materials for UV photodetectors owing to suitable bandgaps, environmental stability, eco-friendliness, and cost-effectiveness. − However, a common challenge in the solution-based fabrication method is the difficulty of controlling the film crystallization, which results in films with high defect concentrations that negatively impact device performance. This poses a hindrance to the further enhancement of performance in these new copper halide-based UV photodetectors. − Extensive efforts have been devoted to developing strategies for controlling crystallization and obtaining high-quality photoactive films. − Among these techniques, antisolvent washing is one of the most popular and efficient methods for crystallization control.…”

“…The photoresponse spectrum in Figure 3b exhibits that our device is highly sensitive to deep-UV photons below 280 nm and blind to photons with wavelengths longer than 350 nm. The rejection ratio (R 245 /R 400 ), which is defined as the ratio of the responsivity (R) at 245 nm and the responsivity at 400 nm, 13 is calculated to be 1200, indicating a superior visible-blind spectral selectivity of our device. The current−voltage (I−V) curves in the dark and under various light intensities of 275 nm are shown in Figure 3c.…”