NiO_x Hole Transport Materials By Magnetron Sputtering And Its Applications For Perovskite Solar Cells

Organic-inorganic halide hybrid perovskite materials exhibit excellent properties such as high absorption coefficient,good carrier transport property and adjustable bandgap,etc.Perovskite solar cells(PSCs)have achieved power conversion efficient of 22%over last few years,indicating a great development prospect.The cost and stability are main issues hindering the commercial application of PSCs.In inverted PSCs,acid PEDOT:PSS which can etch the transparent electrode is still used mostly as the hole transport material,thus influence the stability of PSCs.To improve the stability,its’ useful to replace the PEDT:PSS by a p-type semiconductor.Therefore,this work demonstrates the magnetron sputtering NiOx hole transport materials(HTMs)and their applications in PSCs.The main research we finished are as follows:(1)By adopting the PEDOT:PSS as hole transport layer(HTL),we fabricated the inverted PSCs and further study the effects of annealing temperature and solvent ratio of electron transport material toward their photovoltaic performance.It’s found that by annealing CH3NH3PbI3(MAPbI3)layer at 120℃ and using the PC61BM/CB solvent of 30 mg/mL,we obtain best performed PSC whose power conversion efficiency(PCE)is 14.66%.(2)In the atmosphere of pure O2,sputtering Ni target by DC or RF power under room temperature can lead to NiOx films with relatively low resistance and high transmittance,which meet the demands of HTL application.The depositing rates and optical,electric properties of these NiOx were systematically investigated and it’s revealed that the NiOx layer sputtering under RF 100 W possess the lowest resistance.As comparison,NiOx layer sputtering under DC power show approximate transmittance but higher resistances.(3)The sputtering NiOx,layers were applied as HTL to fabricate PSCs.It’s found that PSC based on NiOx layers sputtering by RF 100 W achieved highest PCE of 16.3%with negligible hysteresis.This is mainly ascribed to the low resistance and good carrier transport ability.PSCs based on DC sputtering NiOx achieved average PCE of 12%.Compared with the PEDOT:PSS based PSC,the NiOx based device remained 60%of its initial PCE after being stored for 39 days in air,showing pretty good air stability.The sputtering NiOx films demonstrated in this work show advantages of good hole transport ability and simple low-temperature techniques,thus presenting great prospect in flexible PSCs.However,the NiOx films still show relatively high resistances,which would limit the PCE of PSCs.For higher PCE,the doping method and the interface modification may be used to further improve NiOx properties in following work.