Enhanced Performance of Perovskite Single-Crystal Photodiodes by Epitaxial Hole Blocking Layer

Abstract

Introducing hole/electron transporting and blocking layers is considered to enhance the performance of electronic devices based on organic–inorganic hybrid halide perovskite single crystals (PSCs). In many photodiodes, the hole/electron transporting or blocking materials are spin-coated or thermal-evaporated on PSC to fabricate heterojunctions. However, the heterojunction interfaces due to lattice mismatch between hole/electron, transporting or blocking materials and perovskites easily form traps and cracks, which cause noise and leakage current. Besides, these low-mobility transporting layers increase the difficulty of transporting carriers generated by photons to the electrode; hence, they also increase the response time for photo detection. In the present study, MAPbCl 3 -MAPbBr 2.5 Cl 0.5 heterojunction interfaces were realized by liquid-phase epitaxy, in which MAPbBr 2.5 Cl 0.5 PSC acts as an active layer and MAPbCl 3 PSC acts as a hole blocking layer (HBL). Our PIN photodiodes with epitaxial MAPbCl 3 PSC as HBL show better performance in dark current, light responsivity, stability, and response time than the photodiodes with spin-coated organic PCBM as HBL. These results suggest that the heterojunction interface formed between two bulk PSCs with different halide compositions by epitaxy growth is very useful for effectively blocking the injected charges under high external electric field, which could improve the collection of photo-generated carriers and hereby enhance the detection performance of the photodiode. Furthermore, the PIN photodiodes made of PSC with epitaxial HBL show the sensitivities of 7.08 mC Gy air −1 cm −2 , 4.04 mC Gy air −1 cm −2 , and 2.38 mC Gy air −1 cm −2 for 40-keV, 60-keV, and 80-keV X-ray, respectively.

Solution-Processed Epitaxial Growth of MAPbI3 Single-Crystal Films for Highly Stable Photodetectors

“…And the small picture in Figure 1C shows the interface of the epitaxial layer and substrate. Epitaxial MAPbI 3 SCF with smooth morphology and controllable thickness can be directly grown on MAPbBr 3 single crystal substrate due to good lattice matching (Li et al, 2020;Pan et al, 2020;Xu et al, 2020). As shown in Figures 1D,E Different from MAPbI 3 single crystal of hexagonal structure, the epitaxial MAPbI 3 film changes to cubic structure because of the cubic MAPbBr3 substrate (Wang et al, 2019b).…”

Photo-Diodes Based on CH3NH3PbCl3 Perovskite Single Crystals by Epitaxial Growth for Ultraviolet Photo-Detection

“…Recently, Organic-inorganic hybrid methylammonium lead halide perovskite (MAPbX 3 , where MA = CH 3 NH 3 , and X = Cl, Br, I) perovskite have attracted a lot of attention due to their excellent optoelectronic properties, such as tunable band gap, low trap density, and long diffusion length [1,2]. MAPbX 3 have been proved to have potential in a number of optoelectronic devices, such as photodetectors, light-emitting diodes, and solar cells [3][4][5][6][7][8][9]. There are reports on the visible and near infrared detection applications of MAPbI 3 and MAPbBr 3 single crystals because of their suitable band gap and high optical absorption coefficient [10,11].…”

Biphasic Liquid–Liquid Interface Limit Architecture of High-Quality Perovskite Single-Crystal Sheets for UV Photodetection

“…Surface defects have a greater impact on UV detection because of high UV absorption on the shallow surface. MAPbCl 3 is considered one of the most promising materials for visible-blind UV detectors because of its large optical band gap. − The high growth temperature for MAPbCl 3 single crystals is about 60–100 °C by the antisolvent evaporation method. − Therefore, the low temperature gradient can restrain the growth condition and obtain higher crystal quality . The growth temperature and precursor concentration play key roles in obtaining high-quality bulk single crystals of MAPbX 3 by the reported methods.…”