Research On Perovskite Solar Cells Based On The Electron Transfer Layers Of SnO₂

In the past few years,there have been significant advances in the field of organic-inorganic hybrid perovskite solar cells?PSCs?as the 3^nd generation of solar cells,which have become one of the most promising substitution of silicon solar cells.As for electron transport layers?ETLs?,have tremendous effect on cell devices by their own properties.Nowadays,Titanium dioxide?TiO₂?was the most general material used as ETLs,however,it was unsatisfied for researchers that TiO₂ had low carrier diffusion length and high temperature for fabrication.Hence,the introduction of tin oxide?SnO₂?nanocrystal provided a brand new thought to explore PSCs.Compared to TiO2,SnO2 as a semiconductor material was more stable,and had a greater ability to transport electron,a wider bandgap,a lower position of conduction band?CB?and valence band?VB?,which matched the energy band of absorption layers better.Although SnO₂ had a lot of advantages as ETLs,there were still some shortcomings need to be settled.Thus,a method was described of enhancing the ability of transporting and extracting electron of SnO₂ based on the organic-inorganic planar n-i-p PSCs,and discussed it intrinsically.This paper carried out doping the low-temperature SnO₂?<100??by Nb⁵⁺using a simple method for the first time.Since Sn was a+4 valence state,to achieve doping SnO₂ by N-type doping is bringing in element which has a higher valence state to improve the electronic properties.After doping by Nb⁵⁺,the improvements were not only realized in power conversion efficiency?PCE?,but also in open-circuit voltage and fill factor,in the meantime,the short-current density was increasing with the content of Nb⁵⁺increased as expected.It was obvious that the hysteresis decreased between forward and reverse sweep of J-V curves.By our conjecture,the level of CB of ETLs shifted and matched more perfectly to the CB of perovskite absorption layers due to doping,which dimished the energy barrier of transporting electrons at the perovskite/ETLs interface and suppressed the electrons-holes recombination.To counter these tips,this paper offered characterization and analysis in detail.Now that doping was an effective way to optimize the properties of semiconductor materials,so we doped SnO₂ by following all series of elements,and studied their performance respectively,aim to find out the best element doping into SnO₂ as ETLs based on the organic-inorganic hybrid planar n-i-p PSCs.At the same time,exploring an easy,effective and universal method to dope low-temperature SnO₂efficaciously to modulate electrical conductivity,which was also a convenient way to adjust CB of SnO₂ slightly within a narrow range to match to various perovskite materials and offered a potent way for further development in the perovskite solar cell devices.