| AVS 65th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology Division | Monday Sessions |
| Session NS+2D+AN+EM+MN+MP+PC+RM-MoM |
| Session: | IoT Session: Nanostructured Devices and Sensors |
| Presenter: | Wei Lei, Southeast University |
| Authors: | X. Wang, Southeast University Z. Zhu, Southeast University Q. Li, Southeast University J. Wu, Southeast University X. Zhang, Southeast University B. Wang, Southeast University W. Lei, Southeast University |
| Correspondent: | Click to Email |
Recently, organometallic lead trihalide perovskites have emerged as a new generation of opto-electronic materials. However, the high performance detection for x-ray and gamma-ray with MAPbX3 is still a big challenge. For x-ray and gamma-ray detections, the detectors should have high sensitivity. If the photon counting method is adopted, the high energy resolution and high time resolution are also required. In this work, the large area MAPbBr3 single crystal has been fabricated with a facile methodology. Due to the quite thick active material and large carrier mobility, the x-ray photons and gamma-ray photons can be absorbed with high efficiency. The photo generated electrons and holes can also be collected effectively with the large electric field. To decrease the dark current in the detection, a novel photo-diode structure is proposed here. In crystallization process of MAPbI3 single crystal, the p-n junction can be formed with doping of selenium atoms into MAPbI3 single crystal.
With various temperature method, the 30mm×30mm×7mm MAPbBr3 single perovskite crystal is fabricated. As the experimental results shown, almost all of the 100 keV x-ray photons are absorbed when the MAPbBr3 SPC is 7mm thick. The detection sensitivity is as high as 305 μC Gyair-1cm-2when the anode voltage of x-ray tube is 30 kV .
To reduce the dark current in the detection, two type of photo diode structures have been proposed here. Firstly, a photo diode with structure of Au/TPD/MAPbBr3 PSC/C60/PCBM/Ag has been fabricated with spin coating and sputtering methods. Although the dark current density can be reduced to 20 nA/cm2 with -30V bias voltage, the temporal response time is nearly 50 μs due to the defects on the interfaces between PSC and carriers transport layers. Then, by doping selenium (Se) in MAPbI3 perovskite single crystals (DPC) crystallization process, low dark current p-n junctions were fabricated without any organic layers. This photodiodes gives the high detection sensitivity as 21000 mC Gyair-1cm-2 and 41 mC Gyair-1cm-2 for 60 keV x-ray and 1.33 MeV gamma-ray respectively. In this photodiode, the transition time becomes shorter under higher electric field, and the carrier lifetime also becomes shorter due to the dopant of Se atoms. Finally, the temporal response time is measured as 3 μs by experiments. The FWHM width of energy spectrum is decreased to 3.2%@1330 keV.