Preparation And Photovoltaic Properties Of Perovskite Solar Cells With Silver-Based Multilayer Electrodes

In recent years,organic-inorganic hybrid perovskite solar cells(PSCs)have received widespread attention.Since the perovskite materials were first utilized in solar cells in 2009,the photoelectric conversion efficiency(PCE)of PSCs has been rapidly increased from 3.8%to 25.2%.However,as the PCE gradually approaches its theoretical limit,the researches on PSC has also begun to shift from initially improving its conversion efficiency to improving its stability,reducing its production costs,and expanding its application fields.In this thesis,firstly,aiming to the problem of expensive Au rear electrodes commonly used in PSCs,the MoO_x/Ag was used as rear electrodes to prepare high-efficiency PSCs;Secondly,in order to solve the indium's scarcity and the inherent brittleness of ITO transparent electrodes which are commonly used in the development of flexible PSCs based on low-cost plastic substrates,the indium-free AZO/Cu/Ag/AZO multilayer transparent conductive films(TCFs)were developed and used as the transparent electrode to prepare the flexible PSCs;Finally,considering the wide application prospects of bifacial PSCs in photovoltaic building integration and other fields,the MoO_x/Cu/Ag/MoO_x multilayer TCFs were developed and utilized as the top transparent electrode of bifacial PSCs.The primary significant results are summarized as follow:Using the MoO_x/Ag instead of Au as the rear electrode,the regular structure ternary-cation-mixed PSCs were developed.The MoO_x layer with a high work function was deposited between the Sprio-OMeTAD and the Ag electrode to improve the carrier transport characteristics by vacuum thermal evaporation technique.The effects of the thickness of MoO_x layer on the PSCs performance were studied.The results show that the introduction of the MoO_x layer can improve the photovoltaic performance of the PSCs.As the thickness of the MoO_x layer increases,the PCE of PSCs increases first and then decreases.When the thickness of the MoO_x layer is 9 nm,the series resistance and reverse saturation current density of the prepared PSC are the smallest.At this time,the device performance is the best,and its PCE reaches 18.7%.Indium-free AZO/Cu/Ag/AZO multilayer TCFs were prepared by magnetron sputtering technique,and were utilized to fabricate the PSCs as transparent electrode.The effects of the thickness of the Ag layer and the introduction of Cu seed layer on the characteristics of multilayer TCFs and PSCs were studied.The results show that the introduction of an ultra-thin Cu seed layer can effectively wet the Ag film and reduce the percolation threshold thickness of Ag film.By adjusting the thickness of each layer of the AZO/Cu/Ag/AZO multilayer TCF,the optimum optoelectronic property is obtained for the prepared AZO(40nm)/Cu(1 nm)/Ag(7 nm)/AZO(40 nm)samples,which have an average light transmittance of 85.59%in the 400~800 nm wavelength range and the sheet resistance of 10.5?/sq.The photovoltaic performance of the prepared PSC based on the optimum multilayer TCF is the best,and the PCE of the PSC device prepared on the glass substrate reaches 14.7%which is the highest PCE value in the currently reported PSCs based on ultrathin metal film transparent electrode.The flexible PSC prepared on the PET substrate also has the PCE of 12.3%and shows good mechanical flexibility.After bending 200 times at a bending radius of 10 mm,its PCE can still maintain 90%of the initial value.MoO_x/Cu/Ag/MoO_x multilayer TCFs were deposited by vacuum thermal evaporation technique,and the bifacial PSCs were prepared by using these multilayer TCFs as the top transparent electrodes.The introduction of Cu seed layer and the various thicknesses of Ag and MoO_x layers on the performances of multilayer TCFs and the bifacial PSCs were studied.The results show that before depositing the Ag layer on MoO_x layer using the vacuum thermal evaporation technique,the ultrathin Cu seed layer can also effectively wet the Ag film,and reduce the percolation threshold thickness of Ag film.As a result,the light transmittance of the multilayer TCF is significantly improved,and the sheet resistance is reduced.Considering that MoO_x/Cu/Ag/MoO_x multilayer TCF is used as transparent electrodes of PSC,in order to facilitate the effective extraction of carrier,the MoO_x layer adjacent to the organic hole transport layer cannot be too thick,and its thickness was fixed at 20 nm.By optimizing the thickness of Ag and the top MoO_x layer,the best bifacial PSC having a transparent MoO_x(20nm)/Cu(1 nm)/Ag(10 nm)/MoO_x(30 nm)electrode achieved PCEs of 13.1%and 10.25%when illuminated from the sides of the indium tin oxide and MoO_x/Cu/Ag/MoO_x electrodes,respectively.