Structure And Properties Of Organic-inorganic Hybrid Perovskite Solar Cells Controlled By Composite Doping

Perovskite solar cells have become a hot research hotspot in recent years due to their advantages such as direct band gap,long carrier diffusion length and low exciton binding energy.It has a good prospect in the field of photovoltaic.In recent years,the conversion efficiency of perovskite solar cells has been improved from 3.8%to 25.5%.Although the photoelectric conversion efficiency of perovskite solar cells is still improving,there are still some problems to be solved before it goes to commercialization,such as the toxic Pb in B position;The organic cations of MA or FA can be easily decomposed under high temperature and humidity.Therefore,how to ensure the excellent performance of the material such as good band gap and high open circuit voltage,it is the primary level to improve the stability and reduce toxicity.Doping has been one of the important and effective methods for researchers to improve the performance of perovskite solar cells.In order to improve the stability and reduce toxicity,we choose to doping at the A and B positions at the same time,and the use of Cs⁺instead of organic cations can significantly improve the stability of perovskite materials.Lead(Pb)in position B is replaced by three different cations magnesium(Mg²⁺),cobalt(Co²⁺),indium(In³⁺)to achieve environmental friendly.The electronic and optical properties of Cs?Mg,Cs?Co,Cs and In doped MAPbI₃ are studied in this paper.The outermost electron orbits of three different elements are different and the hybrid methods are different,which are representative.Each material has been optimized in structure,energy band calculation,state density calculation,optical property calculation,and the data processing is carried out after calculation.After the calculation,the corresponding analysis is carried out after the graph characterization,and the following conclusions are obtained:The energy band of the materials obtained by double doping is complex,and does not change linearly with the change of the doping amount of single element.Under the ratio of Cs and Mg,the doping amount of Cs and Mg is 0.25,that is,when two atoms are replaced,the band gap is1.62eV,which is the most close to the ideal band gap in different proportion;In the case of Cs and Co,the band gap is 1.36eV when the doping amount of Cs and Co is 0.375,and the best is ideal band gap in different proportion:in the case of Cs and In,the doping amount of Cs and In is 0.125,and the band gap is 1.44eV when the doping amount of In is 0.375,and the best is the ideal band gap.For the state density,the Cs elements of a-bit after double doping have little contribution to the band and valence band,Mg element of B has little contribution to the band and valence band.In element only shows some weak contribution to the valence band top when the doping amount is large,and the contribution of Co element to the valence band top is the most prominent.When the doping amount is greater than 0.25,it can show obvious contribution,The contribution increases when the doping amount is 0.375,and the metal conductivity is shown across Fermi energy levels.The materials with Cs and Mg have excellent optical properties,good absorption of visible light,and have low reflectivity and low extinction coefficient;The materials with Cs and Co are excellent in visible light absorption,but have high reflectivity and refractive index,which is not suitable for photovoltaic field;The materials with Cs and in are not only good in visible light but also in infrared light.This is not available in other doping cases.For reflectivity and refractive index,it is very small in visible light range,and it is suitable for photovoltaic field.