Organic Component Regulation And Device Performance Based On 2D CsPbI₃ Materials

Inorganic CsPbI₃ materials have become a popular candidate in the photovoltaic field due to their remarkable semiconductor properties and excellent thermal stability,which have attracted extensive attention of researchers.It is commendable that the photoelectric conversion efficiency（PCE）of CsPbI₃ perovskite solar cells（PSCs）as its main representative application has exceeded 20%.However,due to the limited tolerance factor in CsPbI₃ materials（the component Cs⁺size is too small）,it cannot maintain a long-term stable phase structure at room temperature.In view of this,non-volatile bulk organic cations were introduced into CsPbI₃ to tune the intrinsic three-dimensional structure,so that it can be tailored along a specific crystal plane orientation to form a two-dimensional or quasi-two-dimensional structure,thereby improving the phase stability of the material.It should be emphasized that due to the complex and subtle interaction between organic cations and inorganic octahedra in the intrinsic two-dimensional structure,its photophysical process is more complicated,which makes the performance of optoelectronic devices based on this material still insufficient.Therefore,this paper focuses on the design of the organic cation structure,and explores the influence of different conformational organic cation components on the intrinsic two-dimensional structure and the electrical properties.The specific work is as follows:1)Two different types of organic components（monoamine and diamine）were used as spacers to induce the formation of two-dimensional structures,and photovoltaic devices were prepared by using these two types of organic components as active materials,so as to explore the influence of the two different phase structures on the micro scale to photovoltaic performance.It is confirmed that D-J phase CsPbI₃dominated by diammonium organic cations exhibits superior photovoltaic performance and stability compared with R-P phase components due to stronger interlayer coupling.2)Using the D-J phase structure as a template,two new types of aromatic diamine cations with different conformations are designed,and on this basis,the microscopic arrangement and coupling of spacers with different conformations are regulated,and the electronic structure and charge density are further optimized.Thus,excellent out-of-plane charge transport and the fabrication of high-efficiency 2D photovoltaic devices can be achieved.The recording PCE of more than 15%and excellent stability of 2D D-J CsPbI₃ are obtained.3)Take the n=1 D-J phase structure with large exciton binding energy as an example,and apply it to the fabrication of flexible X-ray detectors.To explore the photophysical process and degradation mechanism of intrinsic low-dimensional structures under high-energy electromagnetic radiation.Due to the stability of the low-dimensional phase and excellent semiconductor characteristics,the sensitivity of the two-dimensional perovskite flexible detector is 5624μC/Gy_aircm~2 at 1000 V/mm electric field,the lowest detectable limit is 3.93 n Gy_air s^-1,and the device can be continuously and stably output at a continuous switch of up to 6000 s.