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Spray Deposition of Silver Nanowire Electrodes for Semitransparent Solid-State Dye-Sensitized Solar Cells



Transparent top electrodes for solid-state dye-sensitized solar cells (ssDSCs) allow for fabrication of mechanically stacked ssDSC tandems, partially transparent ssDSCs for building integration, and ssDSCs on metal foil substrates. A solution-processed, highly transparent, conductive electrode based on PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)] and spray-deposited silver nanowires (Ag NWs) is developed as an effective top contact for ssDSCs. The electrode is solution-deposited using conditions and solvents that do not damage or dissolve the underlying ssDSC and achieves high performance: a peak transmittance of nearly 93% at a sheet resistance of 18 Ω/square – all without any annealing that would harm the ssDSC. The role of the PEDOT:PSS in the electrode is twofold: it ensures ohmic contact between the ssDSC 2,2′,7,7′-tetrakis-(N,N-di-p-methoxyphenylamine)9,9′-spirobifluorene (Spiro-OMeTAD) overlayer and the silver nanowires and it decreases the series resistance of the device. Semitransparent ssDSCs with D35 dye fabricated using this Ag NW/PEDOT:PSS transparent electrode show power conversion efficiencies of 3.6%, nearly as high as a reference device using an evaporated silver electrode (3.7%). In addition, the semitransparent ssDSC shows high transmission between 700–1100 nm, a necessity for use in efficient tandem devices. Such an electrode, in combination with efficient ssDSCs or hybrid perovskite-sensitized solar cells, can allow for the fabrication of efficient, cost-effective tandem photovoltaics.