Synthesis of Multichromophoric Asymmetrical Squaraine Sensitizer via C–H Arylation for See-through Photovoltaic

Developing organic molecules as light harvesters is the key for transparent solar cells technologies. In this paper, we have designed and synthesized a novel metal-free near-infrared (NIR) panchromatic asymmetrical squaraine sensitizers (SQ-SPS) with the thieno[3,2-b]thiophene (TT) unit as π-spacer, dicyanovinyl and cyanoacrylic acid unit as acceptor and successfully used this sensitizer for dye-sensitized solar cells (DSSCs) application. We adopted C–H arylation protocol to achieve the final target molecule which allows to avoid conventional and multistep coupling reactions at low-cost. The time-dependent density functional theory (TDDFT) gives an overview of transitions involved and is in good agreement with the experimental UV–vis absorption data of SQ-SPS. The average lifetime of SQ-SPS is 2.45 ns, which is decent value for squaraine dye. SQ-SPS dye alone shows the power conversion efficiency (PCE) of 5.86%, Voc 0.564 mV, Jsc15.00 mA cm–2 and after cosensitization with N3 dye there is a tremendous inc...