Preparation And Optimization Of The Interface Layer For Perovskite Solar Cells

Recently,perovskite solar cells have been developed rapidly based on the excellent photoelectric performance of perovskite materials,and the efficiency has now exceeded 25.2%.The low material cost and simple fabrication process make perovskite a broad commercial development prospects.Research shows that the interface layer material plays a vital role in the perovskite solar cell,which can not only ensure the efficient separation and transport of electron and hole in the perovskite layer,but also improve the stability of the devices.This paper is mainly focused on the interface layer of inverted plannar perovskite solar cell,and aimed to achieve higher power conversion efficiency through the introduction of new materials or optimization of the original fabrication process.The specific research contents are as follows:?1?Naphthalene-diimide selenophene copolymers as efficient solution-processable electron-transporting material for perovskite solar cells.At present,the most commonly used electron transport materials are fullerene and its derivatives,but there are some problems existing in the materials,such as high price,the need for double-layer or multi-layer composite use resulting in complex structures,and poor water and oxygen stability.In order to reduce costs and simplify device fabrication process,three naphthalene-diimide n-type semiconducting polymers?NDI-Se,NDI-Bi Se,NDI-Tri Se?were synthesized by our laboratory.Through a series kind of characterization,these polymers show excellent thermal stability?over 350??,high crystallinity with strong interchain interaction,well matched energy levels to that of perovskite absorbers,and high electron mobility(the highest NDI-Tri Se electron mobility is 3.0×10?^-4 cm?²/V?·s?).Utilizing these polymers as single and solution processed electron transporting layer,the power conversion efficiency of 9.51%,7.66%and 14.0%were achieved from NDI-Se,NDI-Bi Se and NDI-Tri Se.NDI-Tri Se single electron transporting layer device exhibits comparable performance to that of standard device using C_?60/BCP double electron transporting layer?14.6%?,and the device also showed better stability in air.?2?A new highly transparent Ag/MoO₃ interface buffer layer for efficient transparency perovskite solar cells.It is necessary to introduce suitable buffer layer materials in transparent perovskite solar cells in order to maximize the protection of traditional organic transport materials from being destroyed when sputtering transparent electrodes like ITO.Therefore,we combined Ag?1 nm?and MoO₃?3 nm?as buffer layer to build transparent solar cells.The experimental results proved that MoO₃ reacted with Ag and formed Ag₂MoO₄ during the thermal deposition process,leading to a continuous and compact buffer layer.This film showed high transparence with the average transmittance over 84%from 800 to 1400 nm;and importantly,excellent compatible energy levels with adjacent layers that facilitates efficient electron transport while blocking hole.Based on these,the device used Ag?1nm?/MoO₃?3 nm?as buffer layer achieved 14.0%efficient device,improved by 65%compared to Ag?1 nm?only buffer layer device.?3?Comparison of perovskite solar cell hole transport NiO_x layer fabricated by two methods.NiO_xis an efficient,stable,and easy-preparing inorganic hole transport material that is widely used in perovskite solar cells.We adopted the sol method and the calcination method to synthesize the NiO_xhole transporting layer.Through optimization and comparison,both methods can form NiO_x with high purity and good crystallinity;however,the preparation temperature of the calcination method is lower?270??,the film exhibited high transparent and the corresponding devices showed better performance,the highest efficiency reaches 17.1%.