Page 01/21/2018 19:57:35

Congratulations to PhD Student Xin Song on his first Paper!

11/27/2017
Paper: The Influence of Solvent Additive on Polymer Solar Cells Employing
Fullerene and Non-Fullerene Acceptors​

Abstract:

 
Small-molecule-based non-fullerene acceptors (NFAs) are emerging as a new
field in organic photovoltaics, due to their structural versatility, the tunability
of their energy levels, and their ease of synthesis. High-efficiency polymer
donors have been tested with these non-fullerene acceptors in order to fur-
ther boost the efficiency of organic solar cells. Most of the polymer:fullerene
systems are optimized with solvent additives for high efficiency, while little
attention has been paid to NFA-based solar cells so far. In this report, the
effect of the most common additive, 1,8-diiodooctane (DIO), on PTB7-
Th:PC71BM solar cells is investigated and it is compared with non-fullerene
acceptor 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-
tetrakis(4-hexylphenyl)-dithieno[2,3-d:2,3-d]-s-indaceno-[1,2-b:5,6b]di-thio-
phene (ITIC) devices. It is interesting that the high boiling solvent additive
does have a negative impact on the power conversion efficiency when PTB7-
Th is blended with ITIC acceptor. The solar cell devices are studied in terms
of their optical, photophysical, and morphological properties and find out that
PTB7-Th:ITIC devices with DIO results in coarser domains, reduced absorp-
tion strength, and slightly lower mobility, while DIO improves the absorption
strength of the PTB7-Th:PC71BM blend film and increase the aggregation of 
PC71BM in the blend, resulting in higher fill factor and Jsc.​