Diketopyrrolopyrrole-based acceptors with multi-arms for organic solar cells

Abstract

Three small molecules SBF-1DPPDCV, SBF-2DPPDCV and SBF-4DPPDCV consisting of a spirobifluorene (SBF) unit as the core and one, two, and four diketopyrrolopyrrole dicyanovinyl (DPPDCV) units as the arms have been designed and synthesized for solution-processed bulk-heterojunction (BHJ) solar cells. The UVVis absorption and cyclic voltammetry measurement of these compounds showed that all these compounds have an intense absorption band over 300-750 nm with a LUMO energy level at around À3.87 eV. When pairing with PTB7-Th as the donor, devices fabricated based on PTB7-Th : SBF-4DPPDCV blends showed a decent PCE of 3.85%, which is the highest power conversion efficiency (PCE) amongst the three DPP acceptor fabricated devices without extra treatment. Devices with SBF-1DPPDCV and SBF-2DPPDCV acceptors showed lower PCEs of 0.26% for SBF-1DPPDCV and 0.98% for SBF-2DPPDCVrespectively. The three dimensional (3D) structure of SBF-4DPPDCV facilitates the formation of a 3D charge-transport network and thus enables a rational electron-transport ability (1.04which further leads to a higher J sc (10.71 mA cm À2). These findings suggest that multi-arm acceptors present better performance than one-arm or two-arm molecules for organic solar cells.

Performance Enhancement of Quantum Dot Light-Emitting Diodes via Surface Modification of the Emitting Layer

“…It was further confirmed that the cesium carbonate layer could passivate surface defects of the quantum dot layer to improve radiation recombination and device efficiency. According to the curve in Figure.S9, the mobility of the QD film with cesium carbonate is 2.67× 10 8 , and that of the QD film without cesium carbonate is 3.07× 10 8 . − It shows that the Cs 2 CO 3 has little effect on the mobility.…”

Synthesis of 2,5-Dibutyl-3,6-dimethyl-1H,2H,4H,5H-pyrrolo[3,4-c]pyrrole-1,4-dione: A Diketopyrrolopyrrole Scaffold for the Formation of Alkenyldiketopyrrolopyrrole Compounds

“…Since the discovery of diketopyrrolopyrrole (DPP) in 1974 by Farnum et al, it has become one of the most widely used prototypical π-cores for organic electronic devices and high-performance pigments. − The unique optoelectrical properties and good thermo- and photostability of DPP-based compounds have resulted in their extensive utilization in organic semiconductive materials , and fluorescent probes. ,− For example, several applications of DPP-containing compounds in the area of organic field effect transistors (OFETs), − organic photovoltaics (OPVs), − organic light-emitting diodes (OLEDs) − and dye-sensitized solar cells (DSSC) − have been reported. Our group is also interested in DPP-containing polymers as ambipolar materials for application in organic electronic devices .…”