Design And Synthesis Of Organic-inorganic Hybrid Perovskites With X-ray Detection Properties

Recently,organic-inorganic hybrid perovskites（HOIPs）have attracted wide attention due to their outstanding characteristics such as high atomic number,low preparation cost,large mobility and long carrier lifetime,and are considered as the most promising materials for X-ray detection.In this paper,several HOIPs have been synthesized and characterized by the use of 3-methylaminylpropylamine（3-MNPA）,（S）-α-（4-nitrophenyl）ethanamine hydrochloride（S-4-PEA）,6-aminocaproic acid（6-APA）and other compounds.By using a programmed slow cooling technique,the compounds’single crystals of high quality and large size were grown.Based on these single crystals,single-crystal X-ray detectors were assembled to study the X-ray detection performance of the compounds.1.An A^IIB₂X₆ type three-dimensional（3D）perovskite（3-MNPA）Pb₂Br₆（1）was synthesized by using 3-MNPA organic cation.The Centimeter-scale high-quality single crystals of the compound was grown by a programmed slow cooling process.Based on the single crystals,X-ray detectors were prepared.Its X-ray device exhibits excellent detection abilities.Under 5V bias,the detection limit is 894.2 n Gy_air s^-1,and the detection sensitivity is296μC Gy_air^-1 cm^-2,which is better than the reported A^IIB₂X₆ single crystal X-ray detector.In addition,the device has fast response and fatigue resistance.The application of A^IIB₂X₆ type3D HOIPs in high-performance X-ray detection is made possible by this study.2.We constructed a two-dimensional monolayer perovskite（S-4-PEA）Pb I₄（2）and a two-dimensional bilayer perovskite（6-APA）₂Cs Pb₂Br₇（3）based on S-4-PEA and 6-APA organic cations.We also used the programmed slow cooling method to grow large size and high-quality single crystals of the compound,and made planar X-ray detectors based on the grown single crystals to test their X-ray detection performance.According to the findings,2’s single crystal X-ray detector has a detection limit of 625.7 n Gy_air s^-1 and a detection sensitivity of 270μC Gy_air^-1 cm^-2 at 5 V bias.The detection limit of the single crystal detector of 3 is 203.6 n Gy_air s^-1,and the detection sensitivity is 710μC Gy_air^-1 cm^-2 under the same bias.Additionally,the detectors of the two compounds have faster light response speed（800μs and 300μs,respectively）,and better anti-fatigue performance.These two works demonstrate the potential of 2D HOIPs semiconductor materials for X-ray detection.3.Based on 3-MNPA organic cations,we successfully synthesized a D-J type 2D perovskite polar material（3-MNPA）Pb Br₄（4）,and grew millimeter-thick high quality single crystals of the compound by programmed cooling technique.A planar X-ray detector was assembled based on the single crystal preparation,and a photovoltaic voltage of about 0.45V was observed under X-ray.This powerful bulk photovoltaic effect（BPVE）can provide the ideal driving force for the independent separation of photogenerated electrons and holes,thus eliminating the external power supply,which in turn reduces the noise current of the detector and achieves passive detection of low dose X-rays.As expected,the single crystal X-ray detector has a low dark current,achieving a detection limit of 58.3 n Gy_air s^-1 and a detection sensitivity of 123μC Gy_air^-1 cm^-2 under zero bias.This work shows the application of BPVE of HOIPs polar materials in the field of X-ray detection,and provides a new strategy for low dose X-ray passive detection.