Using Additives To Improve The Performance Of MAPbI₃ Perovskite Solar Cells

Recently,the perovskite materials mainly including methylamine lead iodine have attracted great attention from researchers at home and abroad because of their high visible light absorption coefficient and carrier mobility,and facile preparation by solution method.Perovskite solar cells(PSCs)are considered as one of the most prospective industries.By far,the highest certificated efficiency of PSCs has already reached 25.2%.The electron transport layer plays an important role in transferring electrons and suppressing charge recombination of the device.Sn O₂ materials can be processed under low temperature and by solution method,and have excellent electron mobility and visible light transmittance.Sn O₂ is commonly used as electron transport layer material in PSCs.Its preparation techniques and properties play key roles in the performance of PSCs.Additive engineering to improve the photoelectric conversion efficiency of PSCs proved to be an effective method.This paper mainly explores the influence of additives on Sn O₂ electron transport layer and PSCs devices.The specific research contents are as follows:(1)The effect of different dispersion media(ammonia,water,thiourea)and hydrothermal treatment on the photovoltaic performance of Sn O₂ electron transport layer was studied.X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),transmission electron microscopy(TEM),thermogravimetric analysis(TGA)and other methods were used to characterize Sn O₂ and regular planar PSCs.The results showed that the Sn O₂ electron transport layer prepared with ammonia water as the dispersion medium had better electron extraction ability and photoelectric performance.At the same time,the corresponding device also showed good performance(PCE=17.24%,J_SC=21.44 m A/cm²,V_OC=1.03 V,FF=78%),and the device had no obvious hysteresis.(2)The use of two-dimensional transition metal carbide Ti₃C₂ as an additive to adjust the work function of Sn O₂ electron transport layer was studied.The effect of ultraviolet ozone treatment on the work function of Ti₃C₂ and Ti₃C₂/Sn O₂ composite electron transport layer was investigated.X-ray photoelectron spectroscopy(XPS),atomic force microscope(AFM),scanning electron microscope(SEM),contact angle analysis(CA),kelvin probe,electrochemical impedance spectroscopy(EIS)and other characterizations were performed on regular planar PSCs devices.The results showed that the device based on the Ti₃C₂/Sn O₂ composite electron transport layer after ultraviolet ozone treatment for 8 minutes exhibited superior performance(PCE=19.56%,J_SC=23.11 m A/cm²,V_OC=1.02 V,FF=83%).(3)The effect of triethylenetetramine tetrahydrochloride(TEAE)additive on the morphology of perovskite films and the performance of the regular planar devices was studied.The analysis was carried out by using SEM,XRD,UV-vis,PL,TRPL,AFM,EIS and other test methods.The results showed that additives could improve the film-forming quality of perovskite films,reduce the roughness of the films,and increase the coverage of the films.When the volume fraction of TEAE additives was 0.03 vol%,the device performance was the best(PCE=17.5%,J_SC=22.00 m A/cm²,V_OC=1.06V,FF=75%).