Metal halide perovskites have fascinated the research community over the past decade, and demonstrated unprecedented success in optoelectronics. In particular, perovskite single crystals have emerged as promising candidates for ionization radiation detection, due to the excellent opto-electronic properties. However, most of the reported crystals are grown in organic solvents and require high temperature. In this work, we develop a low-temperature crystallization strategy to grow CsPbBr3 perovskite single crystals in water. Then, we carefully investigate the structure and optoelectronic properties of the crystals obtained, and compare them with CsPbBr3 crystals grown in dimethyl sulfoxide. Interestingly, the water grown crystals exhibit a distinct crystal habit, superior charge transport properties and better stability in air. We also fabricate X-ray detectors based on the CsPbBr3 crystals, and systematically characterize their device performance. The crystals grown in water demonstrate great potential for X-ray imaging with enhanced performance metrics.

Organic semiconductors have attracted tremendous attention in the past few years, thanks to their excellent flexibility, solution-processability, low-cost, chemical versatility, etc. Particularly, organic solar cells based on ternary heterojunctions have shown remarkable device performance, with the recent development of nonfullerene acceptor materials. These novel materials are also promising for photodetection. However, there are several key limits facing organic photodetectors, such as relatively large bandgaps, poor charge transport, and stability. In this work, a novel nonfullerene acceptor-CO i 8DFIC-is introduced, blended with a fullerene derivative and a donor to form ternary heterojunctions. After optimization, photodiodes based on such ternary blends exhibit compelling performance metrics, including low dark current, decent responsivity, large linear dynamic range, fast response, and excellent stability. This device performance is actually on a par with the established silicon technology, suggesting great potential for photodetection and imaging.

X-ray detection is widely utilized in our daily life, such as in medical diagnosis, security checking, and environmental monitoring. However, most of the commercial X-ray detectors are based on inorganic semiconductors, e.g., Si, CdTe, and Ge, which require complex and costly fabrication processes. Metal halide perovskites have recently emerged as a set of promising candidates for ionizing radiation detection, owing to the high attenuation coefficient, long carrier lifetime, and excellent charge transport properties. Perovskite single crystals have been successfully implemented in X-ray detection, but the fragile single crystals limit the device fabrication and the integration with a read-out circuit. In addition, it is hard to reach inch-size single crystals for real application. Flexible devices based on perovskite films or composite films have also been reported, but either the thickness or charge transport properties are limited by the solution processes. In this work, we introduced thermal co-evaporation to deposit highly efficient formamidinium lead iodide perovskite films. Considering the trade-off between X-ray absorption and charge transport, we optimized the active layer thickness and achieved large-area and flexible X-ray detectors with state-of-the-art device performance, including extremely low dark current and noise, fast response, and high sensitivity of 142.1 μC Gy air −1 cm −2 .

No abstract

Hybrid organic–inorganic perovskites have made considerable progress for optoelectronic applications in recent years. In particular, novel hybrid perovskites and materials combinations have been devised to overcome the materials and device stability challenges. Recently, pseudohalide salts have emerged as promising additives to enhance the long‐term stability of the photovoltaic devices. It is found that these pseudohalide ions can effectively passivate the crystal grains and hinder the degradation, which also places perovskites in a very interesting space for the consideration of reducing dark current and noise for photodetection. These possibilities provide strong incentives for a detailed study on the performance metrics of perovskite photodetectors with pseudohalide additives. In this work, photodiodes based on formamidinium lead iodide (FAPbI3) with/without pseudohalide ions are fabricated, and the device performance both at room temperature and cooled with liquid nitrogen is evaluated. Interestingly, it is found that the photodetectors incorporated with pseudohalide ions exhibit not only better stability but also hugely improved figure of merit, including extremely low dark current of ≈10 pA, fast response of ≈50 ns, and high detectivity of >1012 Jones. More importantly, compared with control perovskite photodetectors, the devices with pseudohalide additives demonstrate less temperature‐dependence and superior repeatability.