D-A-D structured organic molecules with diketopyrrolopyrrole acceptor unit for solution-processed organic solar cells.
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ABSTRACT:
SUBMITTER: Zhang J
PROVIDER: S-EPMC3949361 | biostudies-other | 2014 Apr
REPOSITORIES: biostudies-other
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Project description:Silicon phthalocyanines (SiPcs) are promising, inexpensive, and easy to synthesize non-fullerene acceptor (NFA) candidates for all-solution sequentially processed layer-by-layer (LbL) organic photovoltaic (OPV) devices. Here, we report the use of bis(tri-n-butylsilyl oxide) SiPc ((3BS)2-SiPc) paired with poly(3-hexylthiophene) (P3HT) and poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) donors in an LbL OPV structure. Using a direct architecture, P3HT/(3BS)2-SiPc LbL devices show power conversion efficiencies (PCEs) up to 3.0%, which is comparable or better than the corresponding bulk heterojunction (BHJ) devices with either (3BS)2-SiPc or PC61BM. PBDB-T/(3BS)2-SiPc LbL devices resulted in PCEs up to 3.3%, with an impressive open-circuit voltage (V oc) as high as 1.06 V, which is among the highest V oc obtained employing the LbL approach. We also compared devices incorporating vanadium oxide (VOx) or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a hole transporting layer and found that VOx modified the donor layer morphology and led to improved V oc. Probing the composition as a function of film layer depths revealed a similar distribution of active material for both BHJ and LbL structures when using (3BS)2-SiPc as an NFA. These findings suggest that (3BS)2-SiPc is a promising NFA that can be processed using the LbL technique, an inherently easier fabrication methodology for large-area production of OPVs.
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Project description:Solution-processable D-π-A-π-D structured two organic small molecules bearing thienyl diketopyrrolopyrrole (TDPP) and furanyl diketopyrrolopyrrole (FDPP) as central acceptor units and cyano on the π-bridge and phenothiazine as the terminal donor units, coded as TDPP-PTCN and FDPP-PTCN, are designed and synthesized. The C-H arylation and Suzuki coupling protocols have been adopted for synthesizing the molecules. Solution-processed organic solar cells (OSCs) were constructed with these molecules as the donors and phenyl-C71-butyric acid methyl ester as the acceptor yielding power conversion efficiencies (PCE) of 4.0% for FDPP-PTCN and 5.2% for TDPP-PTCN, which is the highest PCE reported so far from the small molecular DPP-phenothiazine-based architecture for solution-based OSCs. The effect of heteroatom substitution on thermal stability and optoelectronic and photovoltaic performances is also systematically investigated herein. This work demonstrates that replacement of oxygen with sulfur in these kinds of small molecules remarkably improves the photovoltaic performance of OSCs.
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