Regioisomeric Effects of Donor-Acceptor-Acceptor’ Small-Molecule Donors on the Open Circuit Voltage of Organic Photovoltaics was written by Che, Xiaozhou;Chung, Chin-Lung;Liu, Xiao;Chou, Shu-Hua;Liu, Yi-Hung;Wong, Ken-Tsung;Forrest, Stephen R.. And the article was included in Advanced Materials (Weinheim, Germany) in 2016.Name: 2,3-Dibromobenzo[b]thiophene This article mentions the following:
We have elucidated the structure-property performance relationships of highly dipolar d-a-a’ small mols. used in organic donor-acceptor heterojunctions. Specifically, the mols. introduced with anti and syn asym. heteroacenes as coplanar donors of BTDC were used to investigate mol. regioisomeric effects on photogeneration efficiency when blended with fullerene acceptors. Both mols. pack in an antiparallel arrangement to achieve a centroymmetric dimer, leading to a net dipole moment of zero. The synBTDC with a shorter backbone conjugation length exhibits a reduced intra- and intermol. charge transfer compared with antiBTDC. An optimized OPV based on antiBTDC:C70 blend achieves VOC = 0.91 α 0.01 V, FF = 0.56 α 0.01, and PCE = 7.2 α 0.3%. Despite the reduced charge transfer and blue-shifted absorption which lead to smaller JSC, synBTDC shows a lower HOMO energy with higher VOC = 1.01 α 0.3 V, with a power conversion efficiency of 6.1 α 0.3%. The design of PYDC leads to a further enhanced VOC = 1.06 α 0.01 V due to the reduced quinoidal character of pyrimidine. We find that the VOC of the d-a-a’ donor:C70 devices is a function of the donor conjugation length: a reduction of backbone conjugation lowers the HOMO level for both groups of mols. with embedded benzothiadiazole or pyrimidine central “a” unit, leading to an enlarged donor-acceptor HOMO-LUMO gap and a larger VOC. Shortening the alkyl chains, or raising their LUMO energy for more complete exciton dissociation may lead to further improvements in FF, and ultimately the device performance. In the experiment, the researchers used many compounds, for example, 2,3-Dibromobenzo[b]thiophene (cas: 6287-82-7Name: 2,3-Dibromobenzo[b]thiophene).
2,3-Dibromobenzo[b]thiophene (cas: 6287-82-7) belongs to benzothiophene derivatives. Benzothiophene is a fused ring compound of thiophene ring and benzene ring, which is an important class of heterocycles with advantageous structures. Its aromaticity makes it relatively stable, although as a heterocycle, it has reactive sites which allow for functionalization.Name: 2,3-Dibromobenzo[b]thiophene
Referemce:
Benzothiophene – Wikipedia,
Benzothiophene | C8H6S – PubChem