[1] [1] Scharber M, Mühlbacher D, Koppe M, et al. Design rules for donors in bulk-heterojunction solar cells-towards 10 % energy-conversion efficiency［J］.Advanced Materials,2010,20 (3): 579-583.

[2] [2] Liu Y, Wang H, Liao P, et al. First principles study of electronic and optical properties of copolymers PBDTX-BY (X, Y=O, S, Se, Te)［J］.Physica B: Condensed Matter,2019,575: 311485.

[4] [4] Chiu K Y, Govindan V, Lin L C, et al. DPP containing D-π-A organic dyes toward highly efficient dye-sensitized solar cells［J］. Dyes and Pigments,2016,125: 27-35.

[5] [5] Langa F, Cuesta V, Vartanian M, et al. Increase in efficiency on using selenophene instead of thiophene in p-bridges for D-π-DPP-π-D organic solar cells［J］.Journal of Materials Chemistry A, 2019, 7: 11886-11894.

[6] [6] Yadagiri B, Narayanaswamy K, Srinivasa Rao R, et al. D-π-A-π-D structured diketopyrrolop-yrrole-based electron donors for solution-processed organic solar cells［J］.ACS Omega,2018,3: 13365-13373.

[7] [7] Fabiano E, Sala F D, Cingolani R, et al. Theoretical study of singlet and triplet excitation energies in oligothiophenes［J］. The Journal of Physical Chemistry A,2005,109(13): 3078-3085.

[9] [9] Zhang J, Peng S, Wei Y, et al. A theoretical study of the absorption spectra of electron-deficient pentacene derivatives using DFT and TDDFT［J］.Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy,2020,225: 11780.

[10] [10] Mu Y, Xie Y. Theoretical and experimental comparison of electrical properties of nickel(II) coordinated and protonated polyaniline［J］.The Journal of Physical Chemistry C,2019,123(30): 18232-18239.

[11] [11] Hafner J. Materials simulations using VASP—a quantum perspective to materials science［J］.Computer Physics Communications, 2007,177(1): 6-13.

[12] [12] Perdew J P, Burke K, Ernzerhof M. Generalized gradient approximation made simple［J］.Physical Review Letters,1996,77(18): 3865-3868.

[13] [13] Mazevet S, Torrent M, Recoules V, et al. Calculations of the transport properties within the PAW formalism［J］.High Energy Density Physics,2010,6(1): 84-88.

[14] [14] Henkelman G, Arnaldsson A, Hannes Jónsson. A fast and robust algorithm for Bader decomposition of charge density［J］. Computational Materials Science,2006,36(3): 354-360.

[15] [15] Eslamibidgoli M J, Lagowski J B. The effect of side-chain length on the solid-state structure and optoelectronic properties of fluorene-alt-benzothiadiazole based conjugated polymers-a DFT study［J］.Journal of Physical Chemistry A,2012,116(43): 10597-10606.

[16] [16] Longo L, Carbonera C, Pellegrino A, et al. Comparison between theoretical and experimental electronic properties of some popular donor polymers for bulk-heterojunction solar cells［J］.Solar Energy Materials and Solar Cells,2012, 97: 139-149.

[17] [17] Li Y, Sun B, Sonar P, et al. Solution processable poly(2,5-dialkyl-2,5-dihydro-3,6-di-2- thienyl-pyrrolo［3,4-c］pyrrole-1,4-dione) for ambipolar organic thin film transistors［J］.Organic Electronics,2012,13(9): 1606-1613.

[18] [18] Jung J W, Liu F, Russell T P, et al. Synthesis of pyridine-capped diketopyrrolopyrrole and its use as a building block of low band-gap polymers for efficient polymer solar cells［J］.Chemical Communications, 2013, 49(76): 8495-8497.

[19] [19] Sun J, Wang H, He J, et al. Ab initio investigations of optical properties of the high-pressure phases of ZnO［J］.Physical Review B Condensed Matter & Materals Physics,2005,71(12): 125132.1-125132.5.