Improving the durability of dye-sensitized solar cells through back illumination

Highly efficient and stable back illumination dye-sensitized solar cell (BIL-DSSC) is developed using its Pt-counter electrode (Pt-CE) as the light-irradiating surface. Photovoltaic parameters are measured for DSSCs with Pt-CEs obtained with different sputtering periods of platinum layer. By optimizing the transmittance and catalytic property of the platinum layer on the counter electrode, a light-to-electricity conversion efficiency (η) of 7.54% is achieved with back illumination at 100 mW cm^-2, when the platinum deposition time is 30 s. The effects of platinum layers with different sputtering periods on the photovoltaic characteristics of the respective DSSCs are explained in terms of transmittance and catalytic activity of the layers. A comparative study is also made on the durability of the DSSCs with BIL and front illumination (FIL), in which the respective DSSCs are previously subjected to UV-soaking for different periods of time under simulated conditions of back and front illuminations; at-rest stability tests for such UV-soaked DSSCs carried out through BIL and FIL suggest a far higher stability in favor of the BIL-DSSC, compared to that of the FIL-DSSC. Explanations are substantiated with transmittance spectra, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and absorption spectra.