Abstract
Organic-inorganic hybrid perovskite single crystals (PSCs) have been emerged as remarkable materials for some optoelectronic applications such as solid-state photodetectors, solar cells and light emitting diodes due to their excellent optoelectronic properties. To decrease the dark current, function layers based on spin-coating method are frequently requested for intrinsic PSCs to block the injected current by forming energy barrier. However, the amorphous function layers suffer from small carrier mobility and high traps density, which limit the speed of the photoelectric response of perovskite devices. This work supposes to grow thick MAPbBr3 and MAPbI3 mono-crystalline thin films on the surface of intrinsic MAPbBr2.5Cl0.5 PSCs substrate by a heteroepitaxial growth technique to act as electron-blocking layers. Meanwhile, C60 and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) layers are deposited on the opposite surface of substrate PSCs by spin-coating method to block injected holes. This Au-MAPbI3-MAPbBr3-MAPbBr2.5Cl0.5PSCs-C60-PCBM-Ag heterostructure can be used as excellent X-ray photodetector (XPD) due to its low dark current density of 6.97 × 10−11 A cm−2 at −0.5 V bias, high responsivity of 870 mA/W at −100 V bias and X-ray sensitivity as high as 59.7 μC mGy−1 cm−2 at −50 V bias.
Highlights
The last few years have witnessed the intensive investigation on Organic-inorganic hybrid perovskite single crystals (OIHPSCs) by many researchers due to their advantages of high photons absorption coefficients, high charges mobility and adjustable band gaps (Dou et al, 2014)
We demonstrate that epitaxial perovskite films of high crystallinity could be grown on OIHPSCs
This work demonstrates a perovskite photodetector for X-ray detection fabricated with epitaxial monocrystalline films as electron-blocking layers
Summary
The last few years have witnessed the intensive investigation on Organic-inorganic hybrid perovskite single crystals (OIHPSCs) by many researchers due to their advantages of high photons absorption coefficients, high charges mobility and adjustable band gaps (Dou et al, 2014). Self-powered photodetectors based on p-n junction and heterostructure can work stably without the applied voltage, which results in their improvement. Solution-processed optoelectronic devices have shown lower cost compared to those fabricated by vacuum deposition (Dong et al, 2015a; Miao and Zhang, 2019). OIHPSCs could be grown from solution with bulk size up to centimeter-scale and have shown attractive potential in X-ray detection and gamma ray detection (Wei et al, 2016). Self-powered photodetectors based on solution-processed OIHPSCs tend to have better performance. The previous studies have demonstrated that diverse solution-processed function layers
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