On the study of influence of molecular arrangements and dipole moment on exciton binding energy in solid state

Abstract

Exciton binding energy (Eb) is one of the key factors affecting charge transfer and charge separation in organic solar cells (OSCs). However, most studies on Eb only focus on a single molecule, which is far from the real situation. How molecular arrangements and dipole moment influence Eb in solid state is still an open question. In the present work, a methodology combining the polarizable continuum model with calculated static dielectric constants, optimally tuned long‐range corrected hybrid density functional, and corrected optical gap is proposed for the calculations of Ebs with high accuracy. We have chosen boron subphthalocyanine chloride (subPC) with a strong dipole moment and anthracene without a dipole moment as two representative examples. To simulate solid‐state environmental effects better, different molecular dimers have been built up to simulate molecular arrangements. The most striking finding is that molecular arrangements and dipole moment have evident effects on Ebs. The calculated Ebs of anthracene in dimers are always smaller than that obtained with a single‐molecule model. In contrast, the Ebs of subPC dimers are generally larger (up to 30%) than that of subPC monomer; however, one exception is the convex‐to‐concave dimer configuration with the largest dipole moment, which has a smaller Eb by 5% than the monomer. These findings provide a guideline for the morphology control of thin film to improve the performance of OSC.

Exciton Binding Energy of Non‐Fullerene Electron Acceptors

“…Thus, the molecular packing will affect the E b of organic materials. [ 61 ] For example, Zheng et al [ 62 ] calculated the E b values of the single molecule and dimer of subphthalocyanine chloride (SubPc) ( Figure ) and found that dimer s 3 packing state of SubPc had the smallest E b . Wei et al [ 56 ] reported that the 3D packing crystal of the OSCs could effectively reduce E b with an extremely weak E b of 0.04 eV calculated in 4TIC (Figure 8).…”

“…Thus, the molecular packing will affect the E b of organic materials. [61] For example, Zheng et al [62] Figure 7. a) ϵ r versus frequency of Y6 and Y6-4O, and b) the recently reported OSCs based on high-dielectric-constant organic semiconductors.…”

Designing Potential Donor Materials Based on DRCN5T with Halogen Substitutions: A DFT/TDDFT Study

“…Exciton binding energy is a key factor in influencing charge transfer and separation. The following equations were used to calculate exciton binding energy with IEF-PCM [49,50]:…”

Recent advances and prospects of asymmetric non-fullerene small molecule acceptors for polymer solar cells

“…With the unremit-ting efforts of Zhan Xiaowei's group, 2,2'-[ [6,6,12,12-tetrakis (4-hexylphenyl)-s-indacenodithieno[3,2-b]thiophene]methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)]]bis(propanedinitrile) (ITIC) and 2,2'-2,2'-[(4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis[methylidyne(3oxo-1H-indene-2,1(3H)-diylidene)]]bis[propanedinitrile] (IDIC) (Fig. 1(b)) were reported in 2015 and 2017 respectively, which opened a new chapter in the research of PSCs [14,18] . A series of works have been reported, and the related research results are greatly conducive to the in-depth understanding of PSCs, thus promoting the rapid development of industrial research.…”