Interface Engineering In Sensitized Solar Cells

Sensitized solar cells are multilayer structures in which the interface between layer and layer plays a vital role in the transmission of photogenerated electrons and holes in solar cells.They are the power center of charge transmission,the impact of the positive effect of the cells are significant,but are also the device structure of the main defect center,the negative impact on the cells are impressive.In this paper,different methods are used to modify the interface between the electron transport layer and the photoelectric conversion layer of the sensitized solar cells.Photoanode/dye interface.Several mesoporous TiO₂?MT?materials were synthesized under different conditions following a hydrothermal procedure using Poly?ethylene-glycol?-block-poly?propylene-glycol?-block-poly?ethylene-glycol??P123?as template and titanium isopropoxide as titanium source.The molar ratios of Ti/P123 and the pH values of reaction solution in autoclave were investigated.Various techniques such as Brunauer-Emmett-Teller?BET?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,laser Raman spectrometry?LRS?,scanning electron microscope?SEM?and high resolution transmission electron microscopy?HRTEM?were used to characterize the products.Then,these materials were assembled into dye sensitized solar cells?DSSCs?.The analysis of J-V curves and electrochemical impedance spectroscopy?EIS?were applied to characterize the cells.The result indicated the specific surface area and crystalline structure of materials provided the possibility of high photocurrent for cells,and the structural characteristics of specimen led to the increased electron transfer resistance of cells which was beneficial for the improvement of the photovoltage of DSSCs.The highest photoelectric conversion efficiency of the cells involving MT materials reached8.33%which,compared to that of P25-based solar cell?5.88%?,increased by 41.7%.ETM/perovskite interface.Interfacial engineering of the meso-TiO₂ surface through a modified sequential deposition procedure involving a novel Pb I₂-HMPA complex pretreatment is conducted as a reproducible method for preparing MAPb I₃-based perovskite solar cells providing the highest efficiencies yet reported with polymer HTM layer.Grazing incidence X-ray diffraction depth profile confirmed the formation of a perovskite film with Pb I₂-rich bottom region due to the strong interaction of HMPA with PbI₂,which successfully retarded the dissolution when depositing the perovskite layer on top.We report an average power conversion efficiency of 19.2%?reverse scan,standard deviation s.d.<0.2?over 30 cells?best cell at 19.5%with high FF of 0.80?together with significantly reduced ion migration as indicated by quantitative energy dispersive X-ray?EDX?analysis.Block layer/perovskite interface.The efficiency of perovskite solar cells has been soaring over the past three years and is expected to continue to increase.Efforts to increase the PCE of planar junction perovskite solar cells have been made from different perspective.For the first time,we use wormhole-like mesoporous hexagonal mesoporous silica?HMS?to modify the perovskite layer inside planar junction perovskite solar cell and improve effciency.The formed random islands of HMS decreased the loading of perovskite layer,leading to abnormal growth of perovskite and increased path length of light.With HMS islands in a planar heterojunction device,we realized an average PCE of 17.6%over 30 devices,which is higher than that of controlled intrinsic planar heterojunction device?15.85%?.