The electron acceptor 2-(1,1-dicyanomethylene) rhodanine is a promising alternative to cyanoacrylic acid as an anchoring group for organic dyes. For example, the RD-II-based dye-sensitized solar cell has an overall conversion efficiency of 7.11 % and long-term stability.

Two new benzotriazole-bridged sensitizers are designed and synthesized (BTA-I and BTA-II) containing a furan moiety for dye-sensitized solar cells (DSSCs). Two corresponding dyes (BTA-III and BTA-IV) with a thiophene spacer were also synthesized for comparison. All of these dyes performed as sensitizers for DSSCs, and the photovoltaic performance data of these benzotriazole-bridged dyes showed a high open-circuit voltage (V(oc): 804-834 mV). Among the four dyes, DSSCs based on BTA-II, with a furan moiety and branched alkyl chain, showed the highest V(oc) (834 mV), a photocurrent density (J(sc)) of 12.64 mA cm(-2), and a fill factor (FF) of 0.64, corresponding to an overall conversion efficiency (η) of 6.72%. Most importantly, long-term stability of the BTA-I-IV-based DSSCs with ionic-liquid electrolytes under 1000 h light-soaking was demonstrated, and BTA-II exhibited better photovoltaic performance of up to 5.06% power conversion efficiency.

Der Elektronenakzeptor 2‐(1,1‐Dicyanmethylen)rhodanin bietet als Ankergruppe für organische Farbstoffe eine vielversprechende Alternative zu Cyanacrylsäure. Beispielsweise konnte eine langzeitstabile Farbstoffsolarzelle auf RD‐II‐Basis mit einem Gesamtwirkungsgrad von 7.11 % erhalten werden.

Dye-sensitized solar cells (DSSCs) with cobalt electrolytes have gained increasing attention. In this Research Article, two new pyrido[3,4-b]pyrazine-based sensitizers with different cores of bulky donors (indoline for DT-1 and triphenylamine for DT-2) were designed and synthesized for a comparative study of their photophysical and electrochemical properties and device performance and were also analyzed through density functional theory calculations. The results of density function theory calculations reveal the limited electronic communication between the biphenyl branch at the cis-position of N-phenylindoline and the indoline core, which could act as an insulating blocking group and inhibit the dye aggregation and charge recombination at the interface of TiO2/dye/electrolyte. As expected, DSSCs based on DT-1 with cobalt redox electrolyte gained a higher photoelectric conversion efficiency of 8.57% under standard AM 1.5 G simulated sunlight, with Jsc = 16.08 mA cm(-2), Voc = 802 mV, and FF = 0.66. Both electrochemical impedance spectroscopy (EIS) and intensity-modulated photovoltage spectroscopy (IMVS) suggest that charge recombination in DSSCs based on DT-1 is much less than that in their counterparts of DT-2, owing to the bigger donor size and the insulating blocking branch in the donor of DT-1.

Three sensitizers with N,N-diphenylthiophen-2-amine as the donor were synthesized for use in dye-sensitized solar cells, in which the furan-based sensitizer showed an efficiency of 7.16%.