Jung, Minwoo Seo, Dongkyun Kwak, Kyungwon Kim, Ajeong Cha, Wonsuk Kim, Hyunjung Yoon, Youngwoon Ko, Min Jae Lee, Doh-Kwon Kim, Jin Young Son, Hae Jung Kim, BongSoo 2024-01-20T07:31:08Z 2024-01-20T07:31:08Z 2021-09-05 2015-04 0143-7208 https://pubs.kist.re.kr/handle/201004/125604 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-C-61-butyric acid methyl ester (PCBM) blend film was controlled using post-thermal annealing at 130 degrees C or addition of 1,8-diiodooctane (DIO) additives. The DIO-additive treatment was more effective than thermal annealing at increasing crystallinity; the DIOadditives 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. (C) 2014 Elsevier Ltd. All rights reserved. English ELSEVIER SCI LTD HIGH PHOTOVOLTAIC EFFICIENCY LOW-BANDGAP POLYMERS DIKETOPYRROLOPYRROLE PERFORMANCE BENZODITHIOPHENE UNIT AGGREGATION ADDITIVES CATHODE Structural and morphological tuning of dithienobenzodithiophene-core small molecules for efficient solution processed organic solar cells Article 10.1016/j.dyepig.2014.12.003 1 DYES AND PIGMENTS, v.115, pp.23 - 34 DYES AND PIGMENTS 115 23 34 scie scopus 000350078900004 2-s2.0-84922382145 Chemistry, Applied Engineering, Chemical Materials Science, Textiles Chemistry Engineering Materials Science Article HIGH PHOTOVOLTAIC EFFICIENCY LOW-BANDGAP POLYMERS DIKETOPYRROLOPYRROLE PERFORMANCE BENZODITHIOPHENE UNIT AGGREGATION ADDITIVES CATHODE Organic solar cells Power conversion efficiency Organic semiconductors Conjugated small molecules Crystallinity Nanoscale phase separation