Tricyanofuran-based donoracceptor type chromophores for bulk heterojunction organic solar cells

Tricyanofuran-based small molecules were synthesized through Knoevenagel reaction with formyl heteroaromatic donating moieties and 2-cyanomethylene-3- cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) as a strong acceptor. UVvis absorption demonstrated that the combination of TCF with donating units resulted in an enhanced intra-molecular charge transfer (ICT) transition, which led to long wavelength absorption in the chromophores. The absorption coefficients and the molecular energy levels of the chromophores can be tuned effectively by employing different donating groups. The chromophores were used in conjunction with [6,6]-phenyl C61 butyric acid methyl ester (PC ₆₁BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC ₇₁BM) to fabricate organic heterojunction photovoltaic cells. This solution-processed bulk heterojunction (BHJ) solar cells exhibited a power conversion efficiency (PCE) of 2.44%, a short-circuit current density (J _SC) of 8.74 mA/cm ², and an open-circuit voltage (V _OC) of 0.93 V under simulated air mass 1.5 global irradiation (100 mW/cm ²).