Study On Performance And Stabilization Optimization Of Perovskite Cells And Light-Emitting Devices

Metal halide perovskite with excellent photoelectric characteristics has been widely used in the field of solar cells and light-emitting diodes.In view of the performance and stability issues that need to be resolved in perovskite photoelectric devices,the paper details are as follows:1.In perovskite solar cells?PSCs?,we optimize the performance and stability of perovskite photovoltaic devices by designing new Cross-linked and dopant-free hole transport materials?HTMs?and adjusting the dimensions of the perovskite absorption layer.Among reported HTMs,the best performing Spiro-OMe TAD has the problem of ionic doping leading to a decrease in device stability,and the poor electron blocking capability and acidic etches of commonly used PEDOT:PSS also limit the improvement of device performance.Four diphenylamine derivatives with a fluorene core were synthesized in the experiment.HTMs that are endowed with vinyl crosslinking units can form insoluble 3D networks under mild annealing temperature of 160?,which improve the solvent resistance during the device fabrication and morphological stability.Hence,the optimized devices incorporating crosslinked HTMs exhibit an impressive power conversion efficiency of 18.7%with a high J_scof 20.89m A/cm²,V_ocof 1.15V and FF of77.8%,which are superior to those of PEDOT:PSS based PSCs.The ultraviolet photoelectron spectroscopy measurement justifies that the new HTMs feature deep HOMO levels aligning well with the perovskite.Moreover,the hydrophobic nature of the synthesized HTMs favors the formation of large grained and continuous perovskite films with good surface coverage,evidenced by the water contact angles and film morphology measurements.Steady-state and time-resolved photoluminescence studies also reveal that fast charge transfer and suppressed recombination occur between the perovskite and HTMs.Our studies demonstrate that employing crosslinked organic HTMs is a promising approach to achieve high efficiency and stable PSCs.In the intrinsic absorption layer of perovskite,the quasi 2D multiple quantum wells?MQWs?structure is a strong candidate for obtaining efficient and stable PSCs.We found that fluorine-substituted phenylethylammonium?FPEA?can effectively control the growth orientation of perovskite crystals and to promote the charge transport in the vertical direction,which is mainly manifested as an increased J_sc?11.70?15.27 m A/cm²?.Furthermore,the hydrophobicity of FPEA is conducive to improving the film morphology,and the humidity stability test also proves that the corresponding photovoltaic device has more excellent stability.2.In perovskite light-emitting diodes?PeLEDs?,we provide a new method to achieve optimized performance and stable emission wavelength by introducing two different organic cations.First,the mixed dimension Cs Pb Br₃perovskite film featuring the reduced grain size was formed by employing?S?-?-?-?-Methylbenzylamine bromide?S-MBABr?as the organic spacer cation.Second,doping a small amount of?S?-?-?-Tryptophan bromide?S-Trp Br?additive as passivator to optimize the surface morphology.We demonstrate that the synergistic effect of the-NH3⁺and the-COO^-groups in S-Trp Br can efficiently decrease surface roughness and suppress non-radiative recombination losses caused by defects.Finally,the surface passivated PeLED achieved a significant performance improvement,its current efficiency reached 30.83cd/A and an external quantum efficiency of 10.33%,as well as the electroluminescence spectrum shows decent color purity?FWHM?17nm?.After this,we applied a similar dual-cation strategy to Cs Pb I₃perovskite.The phase distribution changes in the quasi-2D film through the simple mixing of phenylethylammonium?PEA?and1-naphthylmethylamine?NMA?,thereby adjusting the luminescent properties of the device.As a result,displayed red PeLEDs with a peak luminous efficiency of 4.9cd/A and emission wavelength at 632 nm was realized.In our device,the emission spectrum maintains good stability under operating conditions due to the absence of Br/I phase separation.Such strategy provides guidance for solving the stability problem of display red emission and enhancing the luminous performance of PeLED devices.