Polyoxometalates as electron—Transport materials in phthalocyanine—Sensitized solar cells

Although the electron-transport materials (ETMs) used in the solar cells are generally metal oxides such as TiO2, ZnO and SnO2, polyoxometalates (POMs) with similar energy band to metal oxides, rich structures, high thermal stability and low-cost, may become promising candidates for new-type ETMs. In this work, we investigate the electron-transport properties of the pristine POMs, including Keggin-type, Dawson-type and metal-substituted Keggin-type POMs, by means of the measurements of J-V curve, electrochemical impedance spectroscopy and open-circuit voltage decay measurements. The electron-transport ability of POMs increases in the order of PW10Ti2 ﹤ PW11Ti ﹤ PMo12 ﹤ P2Mo18 ﹤ PW12 ﹤ P2W18, suggesting that the electron-transport ability of POM depends on its molecular structure and elemental composition. Among them, the P2W18 has the best electron-transport property. These research results provide valuable information for further exploring the potential application of POMs as ETMs in the solar cells.