Study On Interface Materials Of Hybrid Solar Cells

Organic Inorganic hybrid solar cells have a great research and application value in the new energy field because of their simple preparation process and low cost.In recent years,organic inorganic hybrid solar cells,including polymer solar cells,perovskite solar cells,antimony sulfide solar cells,have been intensively studied.In this thesis,in order to optimize the fabrication process and performance of organic inorganic hybrid photovoltaic devices,we studied the relationship between materials and device performances based on the preparation and application of different interface transporting materials.Interface transporting materials with excellent photoelectric properties,high mobility and suitable bandgap are studied and used for solar cells to enhance efficiency and stability.This work demonstrates highly transparent,high mobility and phase pure Cu2O nano-crystal films are promising HTMs for efficient OSC applications.The Cu2O films are synthesized by reactive magnetron sputtering at room temperature.The highest power conversion efficiency of OSCs based on classical PTB7:PC71BM active layer reaches 8.61%with the Cu2O HTM,which is 15%higher than that of the OSCs with standard PEDOT:PSS HTM layer.Our study shows that the device based on Cu2O HTM exhibited better energy level alignment,reduced series resistance and therefore improved charge extraction compared with those based on CuO and PEDOT:PSS HTM layers.An organic-inorganic integrated hole transport layer(HTL)composed of a semicrystalline 5,6-difluorobenzothiadiazole based conjugated polymer FBT-Th4 and cuprous oxide(Cu2O)is successfully incorporated into conventional structured organic solar cells(OSCs).The optimized OSCs show a high power conversion efficiency up to 9.56%and good stability under ambient conditions.We successfully constructed a heterojunction structure composed of Ag2S nanocrystals/P3HT conjugated polymer with a relatively high absorption coefficient and broader absorption from the ultraviolet to near-infrared region.The assembled P3HT:Ag2S devices exhibited outstanding short-circuit current density around 19 mA·cm-2.Meanwhile,we demonstrate that low-temperature solution-processed nanocrystalline SnO2 thin film prepared by a facile synthesis method can be an excellent electron transport layer(ETL)material for hybrid solar cells.The SnO2 based hybrid solar cells exhibit an open circuit voltage of 280 mV,which was 100 mV higher than that devices without SnO2.Based on above work,we hypothesized the higher power conversion efficiency is due to excellent properties of nanocrystalline SnO2 films,such as high electron mobility and excellent transparency at visible wavelength and enhanced exciton dissociation efficiency,better energy level alignment between FTO and Ag2S for greater photovoltage retention.We report a strategy for reducing heterogeneity by using an organic-inorganic integrated hole transport layer(HTL)composed of the solution-processable conjugated polymer FBT-Th4 and copper oxide(CuxO).The optimized PSCs show significant performance enhancement with power conversion efficiency up to 18.85%from a reverse voltage scan and stabilized champion efficiency of 18.24%with negligible hysteresis.Moreover,we observe a significant enhancement of the long-term stability of perovskite solar cells under high humidity of 70-80%in air.We introduce an in situ method with a new nonfullerene small molecule(IT-4F)that can effectively passivate ionic defects of hybrid perovskite with their positive-charged components under-coordinated Pb2+,during the anti-solvent process of perovskite film formation.This efficient defect passivation reduces the charge trap density and elongates the carrier recombination lifetime.Furthermore,it reduces the open-circuit-voltage deficit of the p-in-structured device,and boosts the efficiency to a value of 18.3%.Moreover,the defect healing also significantly enhances the stability of films in ambient conditions.