Investigation On Stability Of Perovskite Optoelectronic Devices Based On Phosphate Ester Additives

Perovskite solar cells(PSCs)possess excellent light absorption ability,wide absorption wavelength and high carrier mobility.Up to now,their power conversion efficiency has achieved to 25%.Perovskite solar cells are widely considered as promising photovoltaic devices to replace the traditional silicon-based solar cells due to their low manufacturing cost,large-scale production and flexible substrate.Perovskite light-emitting diodes(PeLEDs)is promissing light-emitting devices with high photoluminescence quantum efficiency(internal quantum efficiency is close to 100%)and narrow emission linewidth.External quantum efficiencys(EQEs)of green and red PeLEDs have exceeded 20%,and EQE of blue PeLEDs have also achieved 12%.Therefore,Pe LED shows great application potential in the field of display.However,improving the long-term stability of PSCs and PeLEDs to meet the requirements of commercial application is still challenging.(1)The photoelectric conversion efficiency(PCE)of CsPbI₂Br perovskite solar cell has exceeded 16%,but the problem of water and oxygen stability has severely restricted its commercial development.In this context,we introduced 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)into the perovskite as an additive to improve the long-term stability of CsPbI₂Br perovskite.The results showed that the modified perovskite solar cells achieve a PCE of 11.04%,and maintained 87%of the original efficiency after a10 days storage,while the reference device only kept 80%of the original efficiency.(2)We introduce a new additive 10-dioxo-9-oxa-10-phosphaphenanthrene-10-oxide(DIDOPO)to improve the PeLEDs performance via optimization of the perovskite morphology.Attributing to the chemical interaction between P=O functional group and Pb atom in the perovksite,the perovskite films involving DIDOPO show more dense and smoother morphology than that of the reference film,which lead to reduced leakage current and good contact with the adjacent charge transport layers.Furthermore,DIDOPO helps passivate the trap states and thus suppress the defect-assisted non-radiative recombination.As a result,the maximum external quantum efficiency(EQE)of the blue perovskite light emitting diodes(PeLEDs)achieves 4.11%,and the brightness reaches 737.69cdm^-2,while the reference device shows the maximum EQE of 3.87% and the brightness of 360.32cdm^-2.Moreover,the addition of DIDOPO is able to improve film hydrophobicity,which can enhance the ability of perovskite film to resist water erosion,and ultimately improve the stability of PeLEDs.At an initial luminance of 350cdm^-2,the device life(t₅₀)time of passivated device is up to 215 s,while the t₅₀time of the reference device is 120s.