Rational Design and Characterization of Symmetry-Breaking Organic Semiconductors in Polymer Solar Cells: A Theory Insight of the Asymmetric Advantage

Abstract

Asymmetric molecule strategy is considered an effective method to achieve high power conversion efficiency (PCE) of polymer solar cells (PSCs). In this paper, nine oligomers are designed by combining three new electron-deficient units (unitA)—n1, n2, and n3—and three electron-donating units (unitD)—D, E, and F—with their π-conjugation area extended. The relationships between symmetric/asymmetric molecule structure and the performance of the oligomers are investigated using the density functional theory (DFT) and time-dependent density functional theory (TD–DFT) calculations. The results indicate that asymmetry molecule PEn2 has the minimum dihedral angle in the angle between two planes of unitD and unitA among all the molecules, which exhibited the advantages of asymmetric structures in molecular stacking. The relationship of the values of ionization potentials (IP) and electron affinities (EA) along with the unitD/unitA π-extend are revealed. The calculated reorganization energy results also demonstrate that the asymmetric molecules PDn2 and PEn2 could better charge the extraction of the PSCs than other molecules for their lower reorganization energy of 0.180 eV and 0.181 eV, respectively.

A New Alcohol‐Soluble Polymer PFN‐ID as Cathode Interlayer to Optimize Performance of Conventional Polymer Solar Cells by Increasing Electron Mobility

“…Polymer solar cells (PSCs) have excellent potential to solve the current problem of energy depletion on account of their advantages, for instance, low-cost, roll-to-roll fabrication, and simple solution processing for large-area devices. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] To date, many attempts have been made to obtain efficient PSCs and a lot of effort has been put into them, including interfacial engineering, study of novel donor/acceptor materials, and optimizing the morphology. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] By now, the power conversion efficiency (PCE) of PSCs has exceeded 19%.…”

Improved Performance of Organic Solar Cells by Utilizing Green Non‐Halogen Additive to Modulate Active‐Layer Morphology

“…Compared with traditional silicon solar cells, organic solar cells (OSCs) have many advantages that are difficult to replace: lightweight, translucency, flexible preparation, low cost, large area production, and so on. [ 1–25 ] It can reduce production costs and environmental pollution, and therefore have great potential for solving energy problems and have broad application prospects. Through continuous efforts in donor/acceptor material design and synthesis, interface modification, morphology optimization, and device structure, [ 26–31 ] the power conversion efficiency (PCE) of single‐section OSCs has now exceeded 18%, showing bright prospects for industrialization.…”

Impact of various heterocyclic π-linkers and their substitution position on the opto-electronic attributes of the A–π–D–π–A type IECIO-4F molecule: a comparative analysis

“…In order to study the charge-transfer properties of any molecules, its softness, as well as hardness, could be analyzed. 43 The chemical hardness is basically half of the difference between the ionization potential (IP) and electron affinity (EA) values. These values are also quite notable in determining the HOMO and LUMO energy levels of a molecule, as a low-lying HOMO exhibits high values of IP, and a higher value of EA proclaims a high LUMO.…”