Solution-processed Cuo_x Film As A Hole Transport Layer For Photovoltaic Application

As one kind of new energy,solar energy attracts more and more attention.Scientists are making their efforts to find efficient way to make use of it.Photovoltaic technology inspires high hope for it can convert solar energy directly into electricity.Organic solar cells?OSCs?attract many attentions for the advantages of low price,easy procedure for preparation,flexibility and large scale preparation.Perovskite solar cells?PVSCs?is becoming another hot research topic for its high efficiency in the past few years.However,the issue of bad device stability is the big problem for OSCs and PVSCs going into practical applications.For both OSCs and PVSCs,the contact between active layer and electrode is very important for the device performance and life time.Therefore,it is meaningful to develop new interface materials for the practical application of OSCs and PVSCs.Copper oxides?CuO_x?,including cuprous oxide?Cu2O?and cupric oxide?CuO?,have the advantages of earth-abundant source,low cost and simplicity of preparation.However,CuO_x was prepared through vacuum based deposition method which costs much energy or environmental unfriendly method in previous reports.We develop a facile method for the preparation of CuO_x as a hole transporting layer?HTL?for OSCs and PVSCs to reduce the cost,improve the device performance and stability.We develop a facile and green method to obtain the aqueous solution-processed CuO_x anode buffer layers for highly efficient OSCs.The CuO_x film was prepared from copper?II?acetylacetonate?Cu?CSH7O2?2??CAA?aqueous solution without annealing in ambient air.After H₂O₂ modification and UV-Ozone post-treatment,the resultant CuO_x layer on ITO shows a high work function?5.45 eV?and a high light transmittance in the visible range.The power conversion efficiency?PCE?of the device based on PTB7:PC7,BM system using CuO_x as anode buffer layer reaches 8.68%,which is 10%higher than that of PEDOT:PSS.Moreover,the devices with our CuO_x anode buffer layer exhibit much better stability than the devices with the PEDOT:PSS buffer layer.Solution-processed CuO_x films with high optical transmittance,high work function,proper surface properties and excellent hole-extraction ability are fabricated at low temperature and applied to planar heterojunction perovskite solar cells?PHJ PVSCs?as efficient HTL.The high work function of the CuO,renders the ohmic contact at the MAPbl3/CuO_x interface,reducing VOC loss.Compact and pinhole-free perovskite films with large grain domains are formed due to the proper surface properties,leading to the reduced carrier recombination and thus obtaining high Jsc and VOC.Combining the excellent hole-extraction ability of the CuO_x,high performance PHJ PVSCs with PCE up to 17.43%were demonstrated which is much higher than that of 11.98%based on PEDOT:PSS.The unencapsulated devices based on CuO_x buffer layer maintained 90%of the original efficiency after 650 h in air,showing excellent stability.