Structural and morphological tuning of dithienobenzodithiophenecore small molecules for efficient solution processed organic solar cells

Title
Structural and morphological tuning of dithienobenzodithiophenecore small molecules for efficient solution processed organic solar cells
Authors
정민우서동균곽경원김아정차원석김현정윤영운고민재이도권김진영손해정김봉수
Keywords
Orgnaic solar cells; Power conversion efficiency; Organic semiconductors; Conjugated small molecules; Crystallinity; Nanoscal phase separation
Issue Date
2015-04
Publisher
Dyes and pigments
Citation
VOL 115, 23-34
Abstract
The fused dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene (DTBDT) structure was coupled with diketopyrrolopyrrole (DPP) moieties to generate highly planar bis(2,5-bis(2-ethylhexyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione)dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene (DTBDTDPP-EH) and bis(2,5-bis(2-butyloctyl)-3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione)dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene (DTBDTDPP-BO) molecules, where the EH and BO stands for 2-ethylhexyl and 2-butyloctyl groups respectively. The morphology of the DTBDTDPP-EH alone or DTBDTDPP-EH:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend film was controlled using post-thermal annealing at 130 °C or addition of 1,8-diiodooctane (DIO) additives. The DIO-additive treatment was more effective than thermal annealing at increasing crystallinity; the DIO-additives promoted the formation of nanoscopically well-connected molecular crystalline domains in the blend films. This observation well explained the ordering of the photovoltaic properties of DTBDTDPP-EH:PCBM devices: from worst to best, as-cast, thermally treated, and DIO-treated photoactive films. The DTBDTDPP-BO:PCBM device followed the similar trend with lower performances due to the presence of irregularly overgrown domains. Overall, we demonstrate that it is critical to optimize nanoscale film morphologies by engineering alkyl chains and selecting an appropriate processing method.
URI
http://pubs.kist.re.kr/handle/201004/49205
ISSN
01437208
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KIST Publication > Article
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