A Strategy to Obtain Long-Term Stable Heteropoly Blues for Photosensitive Property Investigations

The photosensitizer is the soul of dye-sensitized solar cells (DSSCs), i.e., the key factor influencing the performance of DSSCs. The commonly used photosensitizers are expensive carboxylic pyridine ruthenium-based complexes, so it is urgent to develop low-cost photosensitizers. Heteropoly blues (HPBs) could be a kind of excellent photosensitizers due to their wide spectra absorption; however, most of them are hardly stable in the air. Here, a strategy of combining the improved vacuum thermal evaporation solid-state reduction (Al as the reductant) and layer-by-layer self-assembly is employed to obtain a series of long-term stable HPBs nanocomposite films (classical Keggin and Dawson HPBs). The photosensitive properties of the obtained HPBs are revealed by optical and photoresponse measurements. Particularly, the obtained HPBs have wider visible light absorption and higher exciton dissociation efficiency, which not only improve the photoresponse of TiO2 ({TiO2}(5)/{PW12}(6)-Al (HPB) film with 28.9 mu A), but also generate high photocurrent ({PEI}(30)/{PMo12}(30)-Re-Al (HPB) film with 130 mu A). Furthermore, the effects of the structure, the elements composition, and the different electron reduction degree on the photosensitive properties have been discussed based on comparison of the photoresponse signals of different HPBs.