Molecular design of D-π-A-π-D small molecule donor materials with narrow energy gap for organic solar cells applications

Ruifa Jin; Xinhao Zhang; Jingfan Xin; Wenmin Xiao

doi:10.1007/s00894-023-05680-8

Molecular design of D-π-A-π-D small molecule donor materials with narrow energy gap for organic solar cells applications

J Mol Model. 2023 Aug 5;29(9):273. doi: 10.1007/s00894-023-05680-8.

Authors

Ruifa Jin^{1

2}, Xinhao Zhang^{3

4}, Jingfan Xin^{3

4}, Wenmin Xiao^{3

4}

Affiliations

¹ College of Chemistry and Life Sciences, Chifeng University, Chifeng, 024000, China. Ruifajin@163.com.
² Inner Mongolia Key Laboratory of Photoelectric Functional Materials, Chifeng University, Chifeng, 024000, China. Ruifajin@163.com.
³ College of Chemistry and Life Sciences, Chifeng University, Chifeng, 024000, China.
⁴ Inner Mongolia Key Laboratory of Photoelectric Functional Materials, Chifeng University, Chifeng, 024000, China.

PMID: 37542668
DOI: 10.1007/s00894-023-05680-8

Abstract

Context: Developing novel materials present a great challenge to improve the photovoltaic performance of organic solar cells (OSCs). In this paper, we designed a series of the donor-π bridge-acceptor-π bridge-donor (D-π-A-π-D) structure molecules. These molecules consist of diketopyrrolopyrrole (DPP) moiety as core, 9-hexyl-carbazole moiety as terminal groups, and different planar electron-rich aromatic groups as π-bridges. The density functional theory (DFT) and time-dependent DFT (TD-DFT) computations showed that the frontier molecular orbital (FMO) energy levels, energy gaps, electron-driving forces (ΔE_L-L), open-circuit voltage (V_oc), fill factor (FF), reorganization energy (λ), exciton binding energy (E_b), and absorption spectra of the designed molecules can be effectively adjusted by the introduction of different π-bridges. The designed molecules have narrow energy gap and strong absorption spectra, which are beneficial for improving the photoelectric conversion efficiency of organic solar cells. In addition, the designed molecules possess large ΔE_L-L, large V_oc, and FF values and low E_b when the typical fullerene derivatives are used as acceptors. The FMO energy levels of the designed molecules can provide match well with the typical fullerene acceptors PC₆₁BM, bisPC₆₁BM, and PC₇₁BM. Our results suggest that the designed molecules are expected to be promising donor materials for OSCs.

Methods: All DFT and TD-DFT calculations were carried out using the Gaussian 09 code. The computational technique chosen was the hybrid functional B3LYP and the 6-31G(d,p) basis set. The benzene and chloroform solvent effects have been considered using the polarized continuum model (PCM) at the TD-DFT level. The simulated absorption spectra of designed molecules were plotted by using the GaussSum 1.0 program.

Keywords: Diketopyrrolopyrrole (DPP) derivatives; Frontier molecular orbitals; Narrow energy gap; Optical and electronic properties; Organic solar cells (OSCs).