Wei Cai,Chun Lin Fu,Rong Li Gao,Wei Hai Jiang,Xiao Ling Deng,Gang Chen
Bismuth ferrite is an important material in ferroelectric photovoltaic field, because of its narrow band gap and large polarization. Doping is a common method to further improve the photovoltaic properties of bismuth ferrite. Mn-doped bismuth ferrite thin films were prepared by sol-gel method. The effects of manganese on the crystal structure, ferroelectric and photovoltaic properties have been investigated. The result indicates that Mn-doped bismuth ferrite thin films are single phase and the lattice constant increases with the increase of manganese content. As manganese content increases, the remnant polarization and coercive electric field increase, while the short circuit photocurrent density and power conversion efficiency decrease. The open circuit photovoltage increases first and reaches the maximum and then decreases as manganese content increases. The results indicate that enhanced ferroelectricity caused by addition of manganese doesn’t make improvement on the photovoltaic characteristic.
Ti-doped bismuth ferrite thin films were prepared via sol–gel spin-coating method. The effects of titanium on the microstructure, optical, leakage, ferroelectric and photovoltaic characteristics have been investigated systematically. The result shows that bismuth ferrite thin films doped with 0–8 at.% Ti are rhombohedral distortion perovskite structure. The addition of titanium inhibits the grain growth and enhances the thickness uniformity and can decrease the band gap of bismuth ferrite thin films. The leakage current of bismuth ferrite thin films is effectively reduced by adding a certain amount of titanium and the leakage mechanism has been investigated. Addition of titanium increases the remnant polarization of the films. As titanium content increases, the short circuit photocurrent density decrease first and then increase, while the open circuit photovoltage increase first and then decrease. The power conversion efficiency of Ti-doped bismuth ferrite thin films increases as titanium content increases, which can be explained as a result of the increased remnant polarization and decreased band gap.
The insertion of a graphene interlayer between van der Waals (vdW) materials could suppress the interlayer recombination to improve interface quality and facilitate charge transport. However, its effect on photovoltaic-mode detectors has rarely been explored. Here, self-powered photodetectors based on WSe 2 /graphene/SnS 2 vdW heterojunctions were assembled and the impact of adding graphene interlayer on its performance was investigated. The p-g-n heterostructure exhibits a photovoltaic characteristic, V OC = 0.13 V and I SC = 0.12 nA under illumination of 2.98 mW/cm 2 @405 nm, lower than that of a control (WSe 2 /SnS 2 ) counterpart ( V OC = 0.19 V and I SC = 1.15 nA). Yet an FF value up to 48.16 % was obtained under an irradiation power density of 0.332 mW/cm 2 @405 nm, which is visibly higher than that of bare WSe 2 /SnS 2 vdW heterostructure . The insertion of graphene interlayer is deemed to reduce the charge traps between vdW materials that are caused by the large concentration difference of majority carriers. However, in case of vdW heterostructure, the subsequently increased leakage current makes the junction less ideal. Thereby interface engineering methods should be used with caution to tune vdW heterostructures on the nanoscale .
危险品化学品经营许可证（带存储）