High Molar Extinction Coefficient Organic Sensitizers for Efficient Dye‐Sensitized Solar Cells

Abstract

We have designed and synthesized highly efficient organic sensitizers with a planar thienothiophene–vinylene–thienothiophene linker. Under standard global AM 1.5 solar conditions, the JK‐113‐sensitized cell gave a short circuit photocurrent density (Jsc) of 17.61 mA cm−2, an open‐circuit voltage (Voc) of 0.71 V, and a fill factor (FF) of 72 %, corresponding to an overall conversion efficiency (η) of 9.1 %. The incident monochromatic photo‐to‐current conversion efficiency (IPCE) of JK‐113 exceeds 80 % over the spectral region from 400 to 640 nm, reaching its maximum of 93 % at 475 nm. The band tails off toward 770 nm, contributing to the broad spectral light harvesting. Solar‐cell devices based on the sensitizer JK‐113 in conjunction with a volatile electrolyte and a solvent‐free ionic liquid electrolyte gave high conversion efficiencies of 9.1 % and 7.9 %, respectively. The JK‐113‐based solar cell fabricated using a solvent‐free ionic liquid electrolyte showed excellent stability under light soaking at 60 °C for 1000 h.

Solid-State Dye-Sensitized Solar Cells Using Red and Near-IR Absorbing Bodipy Sensitizers

“…Also, ruthenium dyes are expensive, and their preparation includes lengthy purification steps. 4 Accurate engineering of the sensitization wavelength would also benefit from a replacement organic dye. Not surprisingly, a large number of laboratories around the world are actively pursuing potential candidates for sensitizers for DSSC applications.…”

Fused-Thiophene Based Materials for Organic Photovoltaics and Dye-Sensitized Solar Cells

“…Efficient organic sensitizers 39 and 40, consisting of a dimethylfluorenylamino-appended thienothiophene-vinylene-thienothiophene unit with aliphatic chains to maintain the planar geometry of the conjugated linker, along with dye 38 comprising a thienothiophene-thienothiophene unit, were synthesized for comparison [47]. This type of structural modification with thienothiophene increased the extinction coefficient of the sensitizer (38, λmax= 372 nm; 39, λmax= 480 nm; 40, λmax= 490 nm) by extending the π-conjugation of the bridging linker as well as augmenting its hydrophobicity, and also increased the stability under long-term light soaking and thermal stress.…”

Incorporation of Thiadiazole Derivatives as π-Spacer to Construct Efficient Metal-free Organic Dye Sensitizers for Dye-sensitized Solar Cells: A Theoretical Study

“…Using sensitizers with high molar extinction coefficients that extend throughout the visible and into the near-IR regions is desirable for efficient solar to energy conversion. Organic sensitizers with long π-conjugations had been demonstrated to augment the molar extinction coefficients and enhance panchromatic light harvesting, thus giving desirable DSSC efficiency and stability [12,15,17,18].…”