Enhancement of power conversion efficiency of dye-sensitized solar cells for indoor applications by using a highly responsive organic dye and tailoring the thickness of photoactive layer

Dye-sensitized solar cells (DSSCs) based on different configurations under various light intensity are characterized, where commercial N719 dye and synthesized D-Dye are used as photo-sensitizer. Regardless of cell configuration, organic D-Dye serves as an efficient photo-sensitizer, giving rise to high cell efficiency comparable with N719. The highest efficiency of 20.98% (Voc of 0.6 V, Jsc of 0.62 mA/cm2, FF of 0.71) is achieved as the front-illuminated rigid DSSC is constructed by applying 8 μm TiO2 layer under 6000 LUX illumination. At the same condition the efficiency of 19.69% (Voc of 0.63 V, Jsc of 0.57 mA/cm2, FF of 0.74) is recorded for N719. Higher efficiency for D-Dye is attributed to high response of its absorption spectrum to the emission spectrum of indoor T5 irradiance. Charge transfer resistance is measured to be 53.1 Ω for D-Dye in conjunction with 8 μm TiO2 which is higher than thicker TiO2 (10 μm and 12 μm) at 0.75 V applied bias under dark condition, indicating that reduction of TiO2 thickness facilitates charge transfer by suppressing charge recombination under low illuminations. A systematic study of the efficiency as a function of key factors like TiO2 thickness, electrode type, and light intensity is explored