Screening efficient organic dyes based on ZL001 by modulating its auxiliary electron acceptor for dye-sensitized solar cells: A theoretical perspective

Based on ZL001 dye, in this work a series of novel organic dyes (denoted M1-M9) were designed by modulating its auxiliary electron acceptors, and then their electronic, optical, and photovoltaic properties were systematically estimated by density functional theory (DFT)/time-dependent DFT (TD-DFT) calculations coupled with Marcus charge transfer model. Results showed that the modulation of auxiliary electron acceptor can efficiently dominate the HOMO-LUMO gap, and dramatically enhance the optical absorption. By exactly estimating the influence of electron injection/recombination on the photocurrent density, the power conversion efficiency (PCE) for ZL001 was estimated to be about 12.90 % with V-oc=837 mV, J(sc)=21.92 mA.cm(-2), and FF=0.703 at the standard solar radiation, which is in good agreement with its measured value of 12.8 +/- 0.1 % (V-oc=887 +/- 6 mV, J(sc)=20.57 +/- 0.18 mA.cm(-2), and FF= 0.700 +/- 0.004). With the same scheme, the predicted PCE value for most of designed dyes was higher than that of ZL001, illuminating that our molecular design is successful. In comparison with ZL001, three newly designed dyes (M7, M8, and M9) with thieno[3,4-b] pyrazine (TPZ), 2,5-dimethyl-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione (DPP), and 5,5'-bithieno[3,4-b]pyrazine (BPZ) as the auxiliary electron acceptor exhibit high PCE values of 19.45 %, 17.63 % and 24.64 % respectively at the AM1.5 G conditions, suggesting that these three dyes are promising candidates for solar cell applications.