Effects Of Anti-solvent On Performance Of CH₃NH₃PbI₃ Perovskite-based Films And Devices

The conversion efficiency of perovskite solar cells has risen from 3.8% to 23.3% in just nine years,which is due to the excellent photoelectric properties of perovskite materials.Among the perovskite materials,the most representative one is methylamine lead iodine(CH3NH3PbI3).The quality of CH3NH3PbI3 film is critical to performance of the solar cells.However,the CH3NH3PbI3 thin films prepared by conventional one-step deposition method are easily to result to low efficiency and poor stability due to very small grain size and poor coverage of the films,which greatly impedes the commercialization of perovskite solar cells.In this thesis,CH3NH3PbI3 thin films with larger grain size were prepared by adding antisolvent on the basis of traditional one-step deposition method,improving both of the conversion efficiency and stability of the devices.This thesis mainly carries out the following research work:(1)Toluene,chlorobenzene and ethyl acetate were used as anti-solvent to prepare CH3NH3PbI3 perovskite films by one-step deposition method.The results showed that the film prepared with toluene as anti-solvent has the largest grain size,the smallest roughness and the highest cell efficiency.The efficiency of CH3NH3PbI3 perovskite solar cells prepared with toluene as antisolvent was 14.66%,while that of the cells without anti-solvent was only 13.90%.(2)The effects of mixed toluene and terpineol as anti-solvent on the growth of CH3NH3PbI3 thin films were studied.The results showed that the addition of terpineol could effectively reduce the growth rate of perovskite films.When adding 10% terpineol to toluene,the grain size of the CH3NH3PbI3 films increased to 600-800 nm,the surface roughness of the films decreased from 26.4 nm to 15.2 nm,and the cell efficiency increased from 14.66% to 18.26%.The stability of the solar cells was significantly improved: 80% of the original efficiency could be maintained after keeping for 20 days in a dark environment with humidity of 40% at 25 ?.(3)Isopropanol was used instead of toluene in the mixed anti-solvent,and the effect of different proportions of terpineol on the film morphology and cell performance was studied.The results showed that when adding 5% terpineol in isopropanol,the prepared CH3NH3PbI3 thin films have small roughness,no pinholes,grain size was up to 500-700 nm,and the cell efficiency was 16.64%.The solar cell could maintain 85% of its original efficiency after keeping for10 days in dark environment with humidity of 40% at 25 ?.