Effect Of Amino Acid And Peptide Small Molecule Passivation On Performance And Stability Of Perovskite Solar Cells

Organic-inorganic perovskite solar cells(PVSCs)show great development potential in photovoltaics due to their low cost and high conversion efficiency.Benefiting from the excellent optical and electronic properties of organic-inorganic perovskite materials,the photoelectric conversion efficiency(PCE)of PVSCs has rapidly increased from 3.8%to 25.7%in the past decade.However,the commercialization of perovskite solar cells still faces some urgent problems.First,the commonly used solution-prepared perovskite films have a large number of grain boundaries and surface defects,which lead to charge recombination loss,so the PCE of PVSCs is far from the Shockley-Quiser limit.Second,factors such as carrier transport imbalance and ion migration cause severe hysteresis,making it difficult to evaluate the real performance of PVSCs.Finally,PVSCs are less stable and difficult to apply in humid environments because water will destroy the perovskite structure.Studies have shown that methods such as interface engineering and additive engineering can improve the efficiency and stability of PVSCs through defect passivation.In this paper,inverted structure PVSCs are selected as the research object,and the device performance can be improved by introducing additives or interface modification layers.The specific research contents are as follows:(1)Using glucosamine hydrochloride(D-GH for short)as a perovskite precursor solution additive to achieve defect passivation and improve the performance of perovskite solar cells.The D-GH additive can significantly improve the quality of perovskite films,which is embodied in increasing the crystallinity of perovskite films and increasing the grain size to form dense perovskite films.In addition,the effects of D-GH additives on perovskite films were studied through various characterizations,and the results showed that D-GH additives were beneficial to the reduction of defect density and the enhancement of absorbance in perovskite films.In addition,D-GH can enhance the hydrophobicity of perovskite films.Benefiting from the above advantages,under the effect of 0.05 mg/m L D-GH,the device efficiency was increased from 17.77%to 20.30%of the control device,and the modified device showed better stability.(2)Four kinds of isoleucine derivatives(DPA for short)with hydrophobic stability are used as the interface layer.According to the different carbon chain lengths,the four isoleucine derivatives are abbreviated as DPA 4,DPA 6,DPA 8 and DPA 10 respectively.After DPA is successfully introduced into the perovskite surface,it can reduce the work function of perovskite MAPb I₃,which is beneficial to charge transport,and DPA can passivate the traps in the perovskite film and inhibit non-radiative recombination.DPA can fill grain boundaries and pinholes,and the alkyl chains on DPA can enhance the hydrophobicity of perovskite films,thereby improving the waterproof and antioxidant capacity of perovskite films.Under the interface modification of DPA,the efficiency and stability of the device are effectively improved,and the performance and stability of the device modified by DPA 10 are the best.The highest efficiency of the device is improved from 17.78%of the control device to 20.31%of the one modified by DPA 10.Under the effect of DPA defect passivation and inhibition of water and oxygen erosion,the stability of the modified device is significantly enhanced.Under the interfacial modification of DPA,a highly efficient and stable perovskite solar cell was successfully fabricated.(3)Four hydrophobic phenylalanine derivatives(PDPA for short)were used as the interface modification layer in the perovskite layer and the electron transport layer.According to the different carbon chain lengths,the four phenylalanine derivatives were abbreviated as PDPA.4.PDPA 6,PDPA 8 and PDPA 10.After optimizing the concentration and screening the PDPA material,we obtained that the device prepared with 4 mg/m L PDPA 10 as the interface modification layer had the best performance with a PCE of 19.38%.Compared with the efficiency of the control device(17.64%),the efficiency of the PDPA 10 modified device is increased by 9%.From the steady-state photoluminescence spectroscopy and time-resolved fluorescence spectroscopy results,it can be concluded that the efficiency improvement of PDPA 10-modified devices is mainly due to the suppressed non-radiative recombination caused by defects,thereby effectively reducing the loss of carrier recombination.Finally,under the protection of the hydrophobic layer and defect passivation,the PDPA 10-modified device exhibits better stability than the standard device,with a PCE decay of only 16%after430 h.Under the interfacial modification of PDPA 10,a high-efficiency and stable perovskite solar cell was successfully fabricated.