Influence of Donor Configurations on Photophysical, Electrochemical, and Photovoltaic Performances in D−π–A Organic Sensitizers

To optimize light harvesting capabilities, one or two indoline units are introduced as additional donors into the traditional D−π–A model and constructed D–D−π–A sensitizers, CQ2 and CQ3. Absorption spectra and cyclic voltammetry are performed to evaluate the influence of different donor configurations on photophysical and electrochemical properties as well as photovoltaic performances. Incorporating the strong electron-donating indoline unit as an additional donor in CQ2 and CQ3 brings several characteristics, such as improving the visible light-harvesting capability and strengthening the intramolecular charge transfer (ICT) process, as well as positively shifting the HOMO energy level. Moreover, CQ3 is more dependent upon coadsorbents. Upon coadsorption with 5 mM CDCA, an obvious increment of more than 160% in Jsc is achieved for CQ3, from 4.26 (without CDCA) to 11.15 mA cm–2 (5 mM CDCA). From photovoltaic performances, dye CQ2 with one additional indoline unit is preferable. Among the three dyes, CQ2 c...