Boosting DSSC efficiency via acid-base co-sensitization with N-1 dye

Abstract

This work presents a comprehensive investigation of a novel organic dye, N-1, as a sensitizer and co-sensitizer in dye-sensitized solar cells (DSSCs) co-sensitized with Ru (II)-based N3 and N719 metal dyes. These co-sensitizers contain a carbazole ring as a donor scaffold linked to an electron-withdrawing pyridyl acceptor. In this study, we demonstrate the significant impact of a base dye (N-1) containing a pyridine anchoring unit on the photovoltaic performance of the standard dyes N3 and N719. This strategy takes advantage of the capacity of the carboxylic and pyridine moieties to attach to the Brønsted-acidic and Lewis-acidic positions of TiO2 interfaces, thereby diminishing the competing adsorption of dyes and augmenting dye deposition on TiO2 surfaces. Consequently, this leads to a reduction in electron recombination and a boost in photovoltage. Additionally, the effect of sensitizer/co-sensitizer concentration on device performance was thoroughly examined. The results indicated that devices fabricated using the co-sensitizer N-1 with sensitizers N3 and N719 at all concentrations outperformed N3 and N719. Notably, the best photovoltaic performance was obtained for the co-sensitized device fabricated using 0.3 mM acid-base N-1 along with N3 sensitizer, displaying a power conversion efficiency of 10.18 % with a short-circuit current density of 19.12 mA.cm−2, open-circuit voltage of 750 mV, and fill factor of 71 %. These findings shed light on the development of new and efficient systems for DSSCs.