Fabrication Of Perovskite Single Crystal Homojunction Photodiode And Phototriode For Photoelectric Properties

The halogenated perovskite CH₃NH₃Pb X₃(X being Cl,Br or I)has attracted extensive attention due to its excellent photoelectric properties and extensive chemical production processes.In particular,the single crystals of MAPb Br₃and MAPb I₃have been shown to have long carrier diffusion lengths and extremely low trap state density.In addition,compared with the heterojunction structure feature,structure is a kind of ideal structural homogeneity,the rectifier with more perfect and photovoltaic properties,this is because the homogeneous junction of photoelectric detector because of its material has the similar band gaps,small interfacial lattice mismatch degree,minimal continuous band structure and defect mode density,in today's devices has important research value,so far,the hybrid perovskite crystal heterostructure has been widely studied,but the preparation of perovskite crystal homogeneity of research are rarely reported.This paper mainly changes the semiconductor properties of perovskite MAPb Br₃through perovskite doping,and then constructs perovskite homojunction photodiode and phototriode,and obtains the following research results:MAPb Br₃was previously reported to be an inherently p-type semiconductor and acts as a p-type substrate in this work.The polyvalent doping of MAPb Br₃crystals can be realized by introducing Bi³⁺ions.Here,based on MAPb Br₃single crystal,we introduce Bi³⁺in the chemical synthesis process to prepare pn photodiode and npn phototriode:(1)(1)After the doping of Bi³⁺ions,the defect density of MAPb Br₃single crystal was basically of the same order of magnitude compared with previous reports,and it did not cause a significant increase in defect concentration.(2)For the photodiode,we find that the device has typical photovoltaic characteristics and can work as a self-driven photodetector.We further improve the performance of the device by adjusting the doping concentration,and the device has a low dark current(4.8×10^-10A)at the doping level of 0.3%without any bias.In addition,the perovskite single crystal photodiode has A high responsivity of up to 0.62 A/W and detectivity of close to 2.16×10¹²Jones.Compared with other MAPb Br₃single crystal devices with similar structure,it has obvious comparability and superiority.(3)We further analyze the MAPb Br₃single crystal phototriode based on pn junction.We know that the photodetector using simple npn or pnp heterojunction/homogeneous junction structure can not only realize the conversion of optical signal,but also can amplify the photocurrent,so as to improve the performance of the device.In addition,there are few reports about perovskite homogeneous junction phototriodes.The magnification of MAPb Br₃single crystal phototriode is 2.9×10³,high responsivity(14.47 A/W)and high external quantum efficiency(3.46×10³).The results show that MAPb Br₃single crystal pn and npn homogeneous junctionphotodetectors provide sufficient guarantee for further experiments and exploratory research,and have potential applications in future optoelectronic devices and systems.