Power conversion efficiency (PCE) is one of the important factors in influencing the overall performance of dye-sensitized solar cells (DSSCs), and precise prediction of PCE is a feasible strategy for preparing highly efficient DSSCs devices. In this work, we designed a series of phenothiazine-based organic dyes by introducing different π-spacers including the 4-isopropyl-4H-dithieno­[3,2-b:2′,3′-d]­pyrrole (DTP) and 2,7-dihydronaphtho­[1,2-d:5,6-d′]­diimidazole (NDI) to tune their photovoltaic properties. The present studies reveal that the PCE value of the DTP-based dye is estimated to be 8.55%, in excellent agreement with the experimentally available value (8.19%) observed in the reported analogue. In comparison to DTP, the strong electron-deficiency NDI group induces a remarkable red-shifting of maximum absorption band, broadening the optical absorption into the near-infrared region. As a consequence, the NDI-based dye achieves an impressive PCE value of 15.51%, which is expected to be a potential organic dye applied in DSSCs.

Studies demonstrate that our designed dyes 3 and 4 exhibit broad optical absorption in the 550–650 nm region and high photoelectric conversion efficiencies of over 32%.

Numerous organic dyes have been developed for dye-sensitized solar cells (DSSCs). However, theoretical screening has not played a due role in designing new dyes. It is mainly attributed that there is rarely quantitative calculation and the inaccurate estimated values for short-circuit current density (J SC) and open-circuit photovoltage (V OC), especially for V OC. In this work, V OC is theoretically predicted by two different models for three D−π–A organic dyes (1, 2, and 3) with the same π bridge and acceptor as well as different donors. Although there is a slight deviation in their structures, their properties are successfully differentiated by accurate quantitative calculations. Dimethoxybenzene-substituted indoline is more suitable as donor than methoxy-substituted triphenylamine and methyl-substituted indoline when it combines with 8H-thieno [2′,3′:4,5]­thieno­[3,2-b]­thieno­[2,3-d]­pyrrole (TTP) as π bridge and cyanoacrylic acid as acceptor. The properties of the donor are not only related to the core group but are also determined by the substituted group. A less than 10% deviation between theoretical and experimental results is an assurance to perform a reasonable prediction for photocurrent–photovoltage.

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The addition of coadsorbents and the introduction of electron-withdrawing groups in dye sensitizers are considered to be feasible strategies for improving the power conversion efficiency (PCE) of dye-sensitized solar cells...