光学仪器  2020, Vol. 42 Issue (6): 59-65 PDF

1. 天津大学 理学院，天津 300355;
2. 天津大学 精密仪器与光电子工程学院，天津 300372

Thin film photoconductive detector based on large grain MA0.7FA0.3PbI3
XUE Yongxiang1, DAI Haitao1, LÜ Qieni2, SIMA Tai1, ZHANG Mingdi2
1. School of Science, Tianjin University, Tianjin 300355, China;
2. School of Precision Instruments and Optoelectronic Engineering, Tianjin University, Tianjin 300372, China
Abstract: In order to study the effect of large grain high-quality perovskite thin films on photodetectors, MA0.7FA0.3PbI3 with a grain size of more than 2 microns was prepared, and a photoconductive photodetector (MCP-PD) was prepared based on the thin film. The photodetector based on the thin film had high responsivity (0.905 A/W) and detectivity (3.18×1012 Jones) at 532 nm and 3 V bias voltage. Under similar conditions, the MCP-PD prepared based on the large grain size film also showed a faster response speed. The experimental results showed that the thin film with large grain size reduced the obstacles of the grain boundary to carrier transport, and improved the responsivity, detection and response time.
Key words: organic-inorganic mixed cation lead halide perovskite    photodetector    high detectivity    grain size

1 实验部分 1.1 MCP钙钛矿前驱体制备

1.2 MCP光探测器（MCP-PD）的制备

1.3 MCP薄膜及MCP-PD器件的性能表征

2 实验结果与讨论 2.1 MCP薄膜的特性表征

 图 1 MCP薄膜的SEM形貌以及XRD图 Figure 1 Surface morphology of perovskite analyzed by SEM and XRD pattern

 图 2 钙钛矿薄膜的吸收和透射光谱 Figure 2 Absorption and transmission spectra of perovskite films.
 $\;\\ \alpha = \frac{{A\sqrt {h\nu - E_{\rm{g}}} }}{{h\nu }}$ (1)

2.2 MCP-PD特性表征

 图 3 光探测器的沟道宽度对响应度和探测度的影响 Figure 3 The influence of the channel width of the photodetector on the responsivity and detectivity.

 $R = \dfrac{{{\rm{ }}{I_{\rm{ph}}}}}{P} = \frac{{{\rm{ }}{I_{\rm{light}}} - {\rm{ }}{I_{\rm{dark}}}}}{P}$ (2)

 $D^* = \frac{R}{{\sqrt {\dfrac{{2q{\rm{ }}{I_{\rm{dark}}}}}{A}} }}$ (3)

 图 4 不同功率密度辐照条件下（波长@532 nm）MCP-PD光电探测器的I-V特性。 Figure 4 I-V characteristics of the MCP-PD photodetector under different power density irradiation conditions （wavelength @532 nm）.

 ${\rm{LDR}} = 20\lg \frac{{{\rm{ }}{J_{\rm{ph}}}}}{{{\rm{ }}{J_{\rm{d}}}}}$ (4)

 图 5 光电流（@ 3 V）与光功率密度的关系曲线 Figure 5 Relation curve of photocurrent （@ 3 V） and optical power density.

 图 6 光探测器的响应速度 Figure 6 Study on the response speed of photodetector.
3 结　论