Research On Interface Modification And Performance Of Perovskite Solar Cells

Perovskite materials have revolutionized the photovoltaic field because of its high absorption coefficient,low exciton binding energy,bipolar carrier transport characteristics,and simple preparation process,and are favored by a large number of researchers.Although the photoelectric conversion efficien cy（PCE）of perovskite solar cells（PSCs）is as high as 25.4%,it is still lower than its theoretical efficiency.Non-radiative recombination in PSCs is the main reason for the above-mentioned efficiency gap.Interface recombination,as a non-radiative recombination,has become one of the significant factors that limit the efficiency of PSCs.In this paper,for the perovskite solar cell based on the Ni O hole transport layer,the modification strategies of the hole transport layer/perovskite layer and the perovskite layer/electron transport layer interface are studied.The main research work and conclusions are as follows:（1）An ultra-thin Ni O interface modification layer was deposited on the Ni O thin film prepared by the combustion method by a hydrothermal method,and a trans-perovskite solar cell with a double-layer Ni O hole transport layer structure was constructed.By changing the hydrothermal reaction time,the thickness and morphology of the Ni O interface modification layer were adjusted to explore its influence on the photoelectric performance of the Ni O hole transport layer,the interface carrier transport characteristics and the photovoltaic characteristics of the device.Compared with the device without the interface modification layer,the optical performance of the double-layer Ni O hole transport layer has less changes,and the electrical conductivity and hole mobility have been improved;the interface recombination of the hole transport layer and the perovskite layer is reduced;the transportation efficiency is improved;the overall photovoltaic performance of the device is significantly enhanced,in which the fill factor is increased and the hysteresis effect is reduced,and the efficiency of the optimized battery device is increased from12.56%to 14.3%.（2）Fmoc-L-leucine containing benzene ring,C=O,-NH-,-COOH and other functional groups is dissolved in ethyl acetate anti-solvent to passivate the surface of perovskite.The functional groups existing in the amino acids can interact with the anions and cations in the perovskite,and improve the photovoltaic performance of the battery device.In this chapter,the effects of Fmoc-L-Leucine concentration on the structure,morphology,photoelectric properties and devices performance of perovskite films are systematically discussed.The results show that Fmoc-L-leucine can partly participate in the crystallization process of perovskite,which is beneficial to eliminate the second phase of perovskite,reduce grain boundary density,and passivate film defects.These advantages are conducive to improving the interface transport capacity of photogenerated carriers in the perovskite layer,thereby improving the photovoltaic performance and long-term stability of the device.Compared with the PSCs without the introduction of amino acid modification,the performance of the device is improved significantly after optimization,and the open circuit voltage is increased from 1.016V to 1.065V,and the efficiency is increased from 13.07%to 15.26%.In the stability study,the unpackaged device can still maintain an initial efficiency of more than 77%after 240h,and maintain a stable output current of 18.53m A cm^-2under a0.82V voltage regulation condition.The device exhibits high environmental stability.（3）The peptide material was applied to the perovskite solar cell for the first time,and the mechanism of Fmoc-FKFKFKFK-NH₂to improve the carrier transport process at the interface of Ni O/perovskite layer was proved.The long chain structure of polypeptide molecules can effectively reduce the transfer energy between molecules,thereby increasing the perovskite grain size.Studies have found that the polypeptide interface modification layer can reduce interface contact resistance,promote interface carrier transport,and can passivate perovskite film surface defects and inhibit non-radiative recombination of carriers,thereby significantly increasing the open circuit voltage of the device.The best perovskite device efficiency based on peptide interface modification can reach 15.14%.In an unencapsulated environment with a relative humidity of 38±5%and a temperature of 20±5°C,the photoelectric conversion efficiency of the device can still be maintained after 240 hours of exposure,and the initial efficiency rate is 78%,showing excellent working stability.