We present a time-saving staining protocol based upon the low-toxicity and nonvolatile solvent dimethyl sulfoxide for a high-efficiency dye-sensitized solar cell, which is very critical for the roll-to-roll flexible cell production. Power conversion efficiencies of 11.7-12.1% were achieved under AM1.5G simulated sunlights. The intrinsic roles of lithium cations on efficiency enhancement were scrutinized by measuring transient absorption and electrical impedance spectroscopies. Our studies have revealed that lithium ions can enhance exciton dissociation at the energy-offset dye/titania interface effectively. Charge collection is not found to be a crucial current loss channel in our high-efficiency dye-sensitized solar cell.

Two perylene anhydride fused porphyrins 1 and 2 have been synthesized and employed successfully in dye-sensitized solar cells (DSCs). Both compounds showed broad incident monochromatic photon-to-current conversion efficiency spectra covering the entire visible spectral region and even extending into the near-infrared (NIR) region up to 1000 nm, which is impressive for ruthenium-free dyes in DSCs.

A novel organic sensitizer JK-225 incorporating a planar indeno[1,2-b]thiophene bridging group was synthesized and compared to its prototype sensitizer JK-2. JK-225 affords a short circuit photocurrent of 13.84 mA cm À2 , an open circuit voltage of 790 mV, and a fill factor of 0.75, corresponding to an overall conversion efficiency of 8.2% under standard AM 1.5 sunlight, which is much higher than that of 6.9% in JK-2.