Research Of High-Efficiency Semitransparent Organic Solar Cells Based On Novel Additives

Bulk heterojunction organic solar cells(OSCs) are considered as a next-generation photovoltaic devices because of their low cost,good flexibility,high transmittance,and adjustable energy level.Among organic solar cells,semitransparent OSCs have attracted more and more attention in recent years.Because it can be applied into the construction industry,the production of windows and other fields.But the main problem to be solved of semitransparent cells is to maximize the transmission of light while achieving high power conversion efficiency(PCE).The introduction of an additive into the active layer is an efficient and simple method of optimizing film morphology and improving device performance.Therefore,we fabricatied high performance OSCs by using new additives.The content of this paper mainly includes three parts,as follows:1.We firstly introduced two new additives,1,8-octanediol(ODO) and 1,10-decanediol(DDO) into PTB7-Th: ITIC non-fullerene system to achieve high efficiency opaque and semitransparent OSCs.When 0.3 wt% ODO or 0.5 wt% DDO was added,opaque devices showed the highest PCE of 10.28% and 9.59% that exhibited a performance improvement of > 31% and > 22%,respectively,compared with reference cells(PCE of 7.84%).Further,semitransparent devices were fabricated by using transparent electrode with PCE of 7.74% and high average visible transmittance(AVT) of 21.35%.In addition,both thermal stability and photostability of OSCs were obviously enhanced by adding ODO/DDO compared with the traditional additives(DIO,CN).2.The dye small molecule SR197(3-(Diethylamino)-7-imino-7H-benzo[4,5]imidazo[1,2-a]chromeno[3,2-c]pyridine-6-car bonitrile) was incorporated as a solid additive into non-fullerene OSCs for the first time.The PCE was improved to 10.29% via doping SR197 into blends of PTB7-Th: ITIC,which exhibited a huge enhancement of approximately 30% compared with the control devices(PCE = 7.92%).In the PBDB-T: ITIC system,the addition of SR197 also improved the photovoltaic performance of devices,achieving a maximum PCE of 11.03%.On this basis,we fabricatied high efficiency and high transmittance semitransparent cells by using a transparent electrode.Among them,the optimal device was achieved with a PCE of 7.77% and AVT of 22.97%.3.To further explore the underlying causes of improved PCE after adding additives.This is due to the carbonyl group of ITIC end groups can react with the dye molecule SR197 to form the N-H…O noncovalent interaction.The existence of intermolecular hydrogen bonds was confirmed using Fourier transform infrared spectra(FT-IR)and two-dimensional proton nuclear magnetic resonance(2D-HNMR).Transmission electron microscopy(TEM) and grazing incidence wide-angle X-ray scattering(GIWAXS) showed the formation of hydrogen bonds can optimized morphology and enhanced crystallinity,which is facilitated to exciton dissociation and charge transmission of OSCs.Herein,three novel additives are reported and high efficiency opaque and semitransparent OSCs were fabricatied by incorporating additive into the active layer,which have certain reference for the research and fabrication of semitransparent cells in the future.