Performance Enhancement Of Planar Perovskite Solar Cells Based On Synergistic Effect Of Additive And Solvent

The perovskite solar cell is an outstanding representative of the third-generation solar cell.The crystal material of perovskite has many advantages such as direct band gap,high efficiency absorption,high carrier mobility,low cost preparation,etc.,which has attracted widely interest of related scientific researchers.This type of solar cell is expected to replace silicon-based solar cells in the future.But if it is truly commercialized,there are many key issues that need to be addressed:Sensitivity of perovskite materials to the atmosphere;large area devices with low conversion efficiency,and so on.In response to these problems,researchers increase the photovoltaic performance and stability of solar cells by enhancing the quality of the perovskite layer,attempting new types of charge transport materials and modifying the device interface.In this paper,high-quality perovskite is prepared with different additives and annealed in solvents,which reduce the defect density and improve the device performance.This paper mainly research is summarized as follows:1.The small molecule Lithium Nitride?LiNH₂?is doped into PbI₂ precursor to change the crystal structure and preferred orientation of PbI₂ film,which improves the conversion of PbI₂ to CH₃NH₃PbI₃ and fabricates high quality CH₃NH₃PbI₃ film.Meanwhile,LiNH₂not only passivates defects,but also optimizes the Fermi energy level and reduces photovoltaic hysteresis effects.Compared to the additive-free device,the Voc of the perovskite solar cell with a doping concentration of 2 wt%is increased from 0.96 V to 1.00V,the Jsc is increased from 18.47 mA/cm² to 20.24 mA/cm²,the FF is increased from 53.3%to 62.0%,the device's PCE is increased from 9.4%to 12.6%.2.1 wt%concentration of 2-chloroethylamine hydrochloride?2-CH?is used to dope the PbI₂ film and CH₃NH₃PbI₃ film.Then further annealed in DMSO to prepare the optimal device.The optimum photovoltaic performance of device is PCE=14.5%,Voc=0.92 V,Jsc=21.10 mA/cm²,FF=74.8%.The high void ratio of PbI₂ film and high quality of CH₃NH₃PbI₃ film are prepared by 2-CH doping and solvent annealing.Comparing the small molecule additive of dimethylamine hydrochloride?DH?,the 2-CH promotes the out-of-plane preferential orientation of the?001?crystal face of the PbI₂ film,which is beneficial to optimizing the performance of CH₃NH₃PbI₃ film and improving the photovoltaic performance of the device.3.The organic small molecule 1,6-hexanediamine dihydrochloride?1,6-DD?is introduced to prepare PbI₂ film with low crystallinity and high out-of-plane preferred orientation.In addition,a large grain size,low defect density and high crystallinity of CH₃NH₃PbI₃ film is prepared by annealing in DMSO atmosphere.The optimal device with concentration of 2 wt%additive is PCE=15.7%,Voc=0.96 V,Jsc=21.94 mA/cm²,FF=74.4%.Compared to the device with no additive and annealing in the air?PCE=10.6%?,the photovoltaic performance is approximately increased by 48.5%.Compared with additive of 1,4-dibutylamine dihydrochloride?1,4-DD?,the results indicate that 1,6-DD forms a complex with PbI₂,which promotes the conversion of PbI₂ and facilitates the formation of the?110?crystal plane of the CH₃NH₃PbI₃ film.The additive increase effectively the current density and the efficiency of the device.