Design of high-efficiency solid-state dye-sensitized solar cells using coupled dye mixtures

A solid-state dye-sensitized solar cell comprising dye mixtures of [Ru(2,2-bpy-4,4′-dicarboxylic acid)(NCS)2] and [Ru(4,4′,4″-tricarboxy-2,2;6,2″-terpy)(NCS)3] on TiO2 thin film was fabricated. The different optical properties of dyes results in increased photocurrent and incident photon to photocurrent efficiency (IPCE). The multiple dye system showed the short circuit current (Isc) of 10.2 mA/cm2 and a cell efficiency ( η ) of 2.8 while broadening the spectral sensitivity of the cell. When a single dye is used, Isc of 6 and 5 mA/cm2 and cell efficiency of 1.7 and 1.2 were observed for [Ru(4,4-bis(carboxy)-bpy)2(NCS)2] (dye 1) and [Ru(2,2′,2″-(COOH)3-terpy)(NCS)3] (dye 2), respectively. Additionally, the resulting IPCE for the solar cell consisting of dye mixture was 50% at wide wavelength range from 530 to 650 nm while for the dye 1, 32% IPCE was observed at 535 nm while for the dye 2, highest IPCE value observed was 20% at 620 nm.