Ultrafast and wideband perovskite photodetectors for imaging in a wide dynamic range

OIHP photo detectors for visualization in the visible and near infrared regions of the spectrum (with an 830-nm long-pass filter), as well as for the image of SITP letters (short for Shanghai Institute of Technology and Physics) under LED illumination. The white and blue lines in the figure represent the normalized intensity of the photocurrent signal. Photo: Chenglong Li, Hailu Wang, Fang Wang, Tengfei Li, Mengjian Xu, Hao Wang, Zhen Wang, Xiaowei Zhang, Weida Hu, Liang Shen

A broadband photodetector with a solution-based processing based on an organic-inorganic hybrid perovskite and volumetric heterojunction of organics is demonstrated, which provides broadband response spectra up to 1000 nm with high EQE in the NIR region, ultrafast response speed of 5.6 ns and wide linear dynamics range of 191 dB. It is encouraging that due to the possibility of imaging in a wide dynamic range, high-quality actual imaging is achieved in the near infrared region of the spectrum, which allows accelerating the transfer of photodetector applications with processing solutions from the laboratory to the image market.

Photodetectors, a key optoelectric component for converting optical signals into electrical signalsThey are of great interest in a wide range of areas: industrial production, military science, biochemical detection, optical communication, etc. Organic-inorganic hybrid perovskites (OIHP) due to their excellent optical and electrical properties, including customizable direct forbidden zone, outstanding optical absorption properties The high carrier mobility and low trap density have attracted enormous research interest for thin-film solar cells, LEDs, and photodetectors. In recent years, OIHP manufacturing and specifications have been improved and photodetectors with high sensitivity, fast response and large linear dynamic range have been recorded. However, in order to circumvent existing restrictions on the visible light detection band arising from the band gap of perovskite material, new device architectures and material systems are needed that provide high performance in a wide spectral range up to NIR.

In a new article published in Light of science and applications, scientists from the State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Technology, Jilin University, China, the State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, the Chinese Academy of Sciences and the University of the Chinese Academy of Sciences, China, and staff have developed new OIHP photodetectors combined with an organic volume heterojunction (BHJ) of suitable band structure, achieving high external quantum efficiency (EQE) exceeding ~ 54% in the NIR region. Due to the low capture density in the light-absorbing layer and the high mobility of the carriers in the transport layer, OIHP / BHJ photodetectors have an ultra-fast response time of only 5.6 nanoseconds by the method of transitional photocurrent (TPC), which can reduce the resistance problem of the time constant of the capacitance.

To further test the possibility of broadband detection and large linear dynamic range (LDR), they adopted OIHP / BHJ photodetectors to create a single-pixel scanning optical imaging system. A high-quality image of complex letter graphics and visible / near infrared radiation of a heat coil are obtained using an OIHP / BHJ photodetector system with large LDR, ultra-fast response speed and room temperature stability. Consequently, modern OIHP photo detectors can speed up the translation of a processed solution photo detector applications from the laboratory to the image market.

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Additional Information:
Chenglong Lee et al., Ultrafast and broadband photodetectors based on perovskite / organic bulk heterojunction for imaging in a large dynamic range, Light: science and application (2020). DOI: 10.1038 / s41377-020-0264-5

Ultrafast and wideband perovskite photodetectors for shooting in a large dynamic range (2020, March 23)
restored March 23, 2020
from https://phys.org/news/2020-03-ultrafast-broadband-perovskite-photodetectors-large-dynamic-range.html

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