A crystalline D-¦Ð-A organic small molecule with naphtho[1,2-b:5,6-b¡ä]dithiophene-core for solution processed organic solar cells

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• 作者：Pranabesh Dutta^a ; Hanok Park^a ; Woo-Hyoung Lee^b ; In-Nam Kang^b ; Soo-Hyoung Lee^a ; ^{shlee66@jbnu.ac.kr}
• 关键词：Small molecules ; Naphtho[12-b ; 5 ; 6-b&prime ; ]dithiophene ; Solution-processable ; Organic solar cells ; Power conversion efficiency
• 刊名：Organic Electronics
• 出版年：2012
• 出版时间：December, 2012
• 年：2012
• 卷：13
• 期：12
• 页码：3183-3194
• 全文大小：931 K

文摘

In this work, we have designed and synthesized a new naphtho[1,2-b:5,6-b¡ä]dithiophene-containing enlarged ¦Ð-conjugated donor-acceptor (D-A) small molecule, NDT(TTz)₂, for use in solution-processed organic photovoltaics. NDT(TTz)₂, which contains a thiophene-bridged naphtho[1,2-b:5,6-b¡ä]dithiophene as the central fused core and triphenylamine-flanked thiophene thiazolothiazole as a spacer, was synthesized via sequential Suzuki and Stille coupling reactions. The thermal, physiochemical, and electrochemical properties of NDT(TTz)₂ have been evaluated by differential scanning calorimetry, thermogravimetry, UV-Vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction, and cyclic voltammetry. As desired for photovoltaic applications, NDT(TTz)₂ possesses good solubility, thermal stability, and a well-ordered, ¦Ð-¦Ð stacked, crystallinity. The optical band gap and HOMO level of NDT(TTz)₂ were determined to be 2.0 eV and ?5.23 eV, respectively. In addition to organic thin film transistor studies, application of NDT(TTz)₂ to preliminary photovoltaic devices has also been investigated by fabricating solution-processed bulk heterojunction solar cells together with PC₇₁BM in a typical layered device structure, ITO/PEDOT:PSS/NDT(TTz)₂:PC₇₁BM/LiF/Al. Without extensive optimization of the device, NDT(TTz)₂ in these devices shows a maximum power conversion efficiency of 1.44 % under AM 1.5 illumination at a 100 mW/cm² intensity.