Research On The Property Of The Methylammonium Lead Bromide-based Solar Cells Prepared At Low Temperature

The organic-inorganic hybrid CH3NH3PbBr3 solar cell has been broadly reported in recent years due to its higher open voltage and excellent stability to humidity and heat.Up to now,the reported efficiency of methylamine lead b new preparation processing to improve their photovoltaic properties.In addition,the romide perovskite solar cells(Br-PSCs)is still low,and it is still necessary to exploreETL of methylamine lead bromine perovskite solar cells are two types,one is fullerene derivatives and the other is TiO2.The poor wettability of perovskite on fullerene layer and fullerene partly dissolution in DMF strongly limited its application in n-i-p structure Br-PSCs.Tio2 is the most widely used ETL in Br-PSCs.However,high temperature annealing is needed to get high quality TiO2 layer.Furthermore,the photochemical catalysis of TiO2 usually decomposes the perovskite film under the UV light irradiation leading to the low stability of PSCs.Therefore,it is desired to develop a new electron transport material to prepare Br-PSCs with n-i-p structure at low temperature.In this study,we prepared the methylammonium lead bromide perovskite solar cells via vapor-assisted solution deposition method and one step anti-solvent method.The results of SEM and AFM showed that the methylammonium lead bromide film prepared by one step anti-solvent method was smoother and flatter.After the layers were assembled into cells,the cell prepared by one step anti-solvent method received 5.88%efficiency,while the efficiency of the cell via vapor-assisted solution deposition method was 3.65%.On the basis of determining the preparation method of thin film,we further optimized the performance of the cell by changing the types of anti-solvent and ionic liquids.Through SEM and UV-vis,it was found that film prepared by toluene was smoother and denser than chlorobenzene,and the light absorption of the film was stronger.Therefore,it was suitable to use toluene as anti-solvent.It was revealed that 1-benzyl-3-methylimidazole chloride can enhance the transmission of FTO and the transmission performance of electrons based on BenMeIM-Cl-IL/C60 structure was better,so the efficiency of the device was higher.Based on the determination of toluene as anti-solvent and 1-benzyl-3-methylimidazole chloride as ionic liquid,a room temperature solution processed IL(BenMeIM-Cl)/C60 bilayer were used as the ETL in planar n-i-p structure Br-PSCs.Owing to the better wettability of the IL/C60 substrate compared to C60 single layer,SEM and AFM characterizations indicated that perovskite film fabricated on IL/C60 structure was denser,smoother.The steady-state PL and TR-PL study revealed that electron transfer from the CH3NH3PbBr3 film to IL/C60 ETL was faster than other three structures(FTO/C60,FTO/C60/IL,FTO/IL).Owing to the advantages of the IL/C60 ETL mentioned above,we have successfully prepared Br-PSCs under low temperature.The efficiency of the champion Br-PSCs based on IL/C60 bilayer was 5.88%with a Jsc of 6.14 mA/cm2,a Voc of 1.39 V,and an FF of 69.94%.The PCE of the device prepared on FTO/IL structure was 1.59%,and the PCE of the device based on FTO/C60 and FTO/C60/IL structure was 2.24%and 2.41%respectively.