Palladium catalyzed direct coupling of 5-bromo-2-furaldehyde with furfural and thiophene derivatives
作者:Tuomo P. Kainulainen、Juha P. Heiskanen
DOI:10.1016/j.tetlet.2016.09.097
日期:2016.11
2-furaldehyde (furfural) and 5-bromo-2-furaldehyde using the air-stable catalyst Pd(OAc)2 and the air-stable ligand P(t-Bu)3HBF4 was examined. The developed procedure was used to functionalize thiophene containing moieties commonly found in organic electronics. The aromatic CH bond activated coupling with 5-bromo-2-furaldehyde afforded novel compounds with useful 5-heteroaryl-2-furaldehyde type functionality
Influence of the Position of the Side Chain on Crystallization and Solar Cell Performance of DPP-Based Small Molecules
作者:Veronique S. Gevaerts、Eva M. Herzig、Mindaugas Kirkus、Koen H. Hendriks、Martijn M. Wienk、Jan Perlich、Peter Müller-Buschbaum、René A. J. Janssen
DOI:10.1021/cm4034484
日期:2014.1.28
Three isomeric a-conjugated molecules based on diketopyrrolopyrrole and bithiophene (DPP2T) substituted with hexyl side chains in different positions are investigated for use in solution-processed organic solar cells. Efficiencies greater than 3% are obtained when a mild annealing step is used. The position of the side chains on the DDP2Ts has a major influence on the optical and electronic properties of these molecules in thin semicrystalline films. By combining optical absorption and fluorescence spectroscopy, with microscopy (AFM and TEM) and scattering techniques (GIWAXS and electron diffraction), we find that the position of the side chains also affects the morphology and crystallization of these DPP2Ts when they are combined with a C-70 fullerene derivative in a thin film. The study demonstrates that changing the side chain position is an additional, yet complex, tool to influence behavior of conjugated molecules in organic solar cells.
The effect of diketopyrrolopyrrole (DPP) group inclusion in p-cyanophenyl end-capped oligothiophene used as a dopant in P3HT:PCBM BHJ solar cells
作者:V. M. Manninen、J. P. Heiskanen、D. Pankov、T. Kastinen、T. I. Hukka、O. E. O. Hormi、H. J. Lemmetyinen
DOI:10.1039/c4pp00207e
日期:2014.10
In this work, two p-cyanophenyl end-capped oligothiophenes, DPP-(2TPhCN)2 and di-(p-CNPh)4T, were compared as dopants in the P3HT:PC60BM bulk heterojunction (BHJ) layer of inverted organic solar cells. Inclusion of DPP-(2TPhCN)2 significantly increased the average efficiency of the solar cells, while the increase using di-(p-CNPh)4T doping in the cell efficiency was minor. In the BHJ photoactive layer, the dopant molecules are close to and interact with P3HT and PC60BM molecules. Intra- and intermolecular interactions of the dopant molecules with P3HT and PC60BM were studied in chloroform solutions. Energy or electron transfer from the dopant molecules to PC60BM takes place as the fluorescence emission intensity and lifetime of the dopant molecules decreased in the presence of PC60BM. In the case of doping with DPP-(2TPhCN)2, doped cells had higher absorbance than the non-doped reference cell and doping broadens the cell absorption to the near IR-region. Thus, the dopant molecules act as additional light absorbers in the photoactive layer and transfer energy or electrons to PC60BM, which increases the short circuit current and power conversion efficiency of the cell. Also, the emission of the cells doped with DPP-(2TPhCN)2 decreased when compared to that of the reference cell. In this case, P3HT can give electrons or energy to dopant molecules and the cell current and efficiency are further increased.