New metal-free organic dye for DSSC devices prepared by electros-pray method: synthesis, characterization and device preparation

Two new metal-free organic dyes CBR and CI with carbazole as electron-donor, thiophene as p- conjugated bridge and 2-cyanoacrylic acid as electron-acceptor and anchor group have been designed and synthesized. After characterized by 1 H NMR, MALDI-TOF, IR and absorption, they were used as sensitizers for DSSCs, in which the TiO 2 anode was prepared by electrospray method. Compared with CBR, the DSSC based on CI showed better performances ( J SC , V OC , FF , and η ). Under AM 1.5 G irradiation, its short circuit current increased nearly 2.6 times, with the power conversion efficiency improving from 1.0% to 2.3%. This is mainly due to the reduction of a CH 2 in the molecular structure, which increased effective conjugation between donor and acceptor, benefiting for the electron transfer from donor to acceptor as well as lowering the material bandgap. Because CBR and CI have stronger absorption in the region of 350-450 nm, they were selected as co-sensitized dye with the conventional dye N719. The power conversion efficiency improved from 5.2% (N719) to 5.6% (CBR-N719) and 6.7% (CI-N719).