Preparation And Performance Optimization Of Inverted Perovskite Solar Cell

Perovskite solar cells?PSCs?have attracted increasing attention around the world because of high power conversion efficiency and low fabrication cost.Compared with common organic semiconductor,organometal halide perovskite solar cells have unique advantages,such as strong absorption coefficients,appropriate and direct band gaps,high carrier mobility,and exceptionally long charge carrier diffusion lengths.The power conversion efficiencies?PCE?of PSC has been excessed 20%,indicating its great potential for future low-cost photovoltaic technology.This paper focuses on improving the energy conversion efficiency of the PSC by modifying the electronic transport layer commonly used in the inverted perovskite solar cells,and the main works are listed as the following aspects:?1?To explore the effect of anti-solvent washing time on the morphology and device performance of perovskite films.The performance of inverted perovskite solar cell was improved by optimizing the time of the solvent washing.The effects of different washing time on the crystallization, optical properties,surface morphology and device efficiency of perovskite films were systematically compared,which laid a foundation for the subsequent work?2?We demonstrated an effective method to enhance the performance of PSC by doping an anthracene-based molecular glass?marked as:ABMG?into PCBM as the electron transport layer ?ETL?.It is found that the uniformity of ETL was improved,which is favorable to the separation of electron-hole pairs.And the good electron transport property of ABMG facilitated the transporting of electron in ETL.With optimized ratio of ABMG,the open circus voltage (V_OC),short circus current(J_SC),fill factor?FF?and PCE of PSC were all enhanced from 0.914V,19.68 mA/cm²,64.01 and 11.51%to 0.871 V,24.82 mA/cm²,59.9%and 12.96%,respectively.These results demonstrate that doping polymer is an effective additive to improve the quality of perovskite films and has great potential to be a new candidate as an easily-accessible additive for mass production of PSCs.?3?The performance of the inverted perovskite solar cell was improved by depositing the polymer PEI on top of the PCBM of the electron transport layer.By optimizing the parameters,in chlorobenzene solvent,spin speed 3000 rpm,under the optimal concentration,the open circuit voltage(V_OC)of PSC,short current(J_SC),the fill factor?FF?and PCE respectively increased by 0.805 V,22.33 mA/cm²,58.71%and 10.55%to 0.942 V,22.43 mA/cm²,75.93 and 16.05%. The increase was as high as 39%.The improvement of energy conversion efficiency is mainly attributed to the improvement of short circuit current and fill factor.The results of UV visible absorption spectra show that the introduction of PEI has no effect on the absorption of the photoactive layer,so the improvement of energy conversion efficiency has nothing to do with the absorption of PEI.The specific efficiency improvement mechanism still needs further research.?4?Using Sn to replace Pb,one step method was prepared for the low-lead perovskite CH₃NH₃Sr_xPb_?1-x?I₃?x=0.1,0.2,0.3?solar cell devices.Through scanning electron microscope ?SEM?,X-ray diffraction?XRD?and optical absorption spectrometry,the all Pb perovskite films and Sn perovskite films were compared.It is found that a small amount of Sn does not change the crystal structure of perovskite,which enhances the absorption capacity of the perovskite layer and improves the film quality of the perovskite layer.But the Sn contained perovskite solar cell is extremely unstable,sensitive to water and oxygen,and Sn²⁺is easily oxidized to Sn⁴⁺.