Showing papers by "Junwu Chen published in 2016"

Aqueous Solution Processed Photoconductive Cathode Interlayer for High Performance Polymer Solar Cells with Thick Interlayer and Thick Active Layer.

Abstract: An aqueous-solution-processed photoconductive cathode interlayer is developed, in which the photoinduced charge transfer brings multiple advantages such as increased conductivity and electron mobility, as well as reduced work function. Average power conversion efficiency over 10% is achieved even when the thickness of the cathode interlayer and active layer is up to 100 and 300 nm, respectively.

Solution-processed small molecules with ethynylene bridges for highly efficient organic solar cells

Abstract: Two acceptor–donor–acceptor (A–D–A) conjugated molecules DPP-E-BDT and DPP-E-BDT-T, using diketopyrrolopyrrole (DPP) as the A-unit, ethynylene bridge flanked benzo-[1,2-b:4,5-b′]dithiophene (E-BDT) as the central D-unit, and different 4,8-substitutions on the BDT were synthesized by Sonogashira coupling reactions for solution-processed organic solar cells (OSCs). The insertion of electron-withdrawing ethynylene bridges (sp hybridization) in the DPP-E-BDT and DPP-E-BDT-T molecules leads to planar and enlarged aromatic skeletons, larger band gaps, and deeper HOMO levels. 4,8-Dithienyl substitution on BDT in DPP-E-BDT-T results in additional conjugation extension to give a slightly smaller band gap compared to the 4,8-dialkoxy substitution in target molecules. Bulk heterojunction solar cells using DPP-E-BDT and DPP-E-BDT-T as the donor materials and fullerene acceptor showed a high open-circuit voltage of 0.89 V and moderate current densities of 10.9 mA cm−2. Besides, quite high fill factors (73.6%) could be obtained. Power conversion efficiencies (PCE) of 7.12% were obtained for DPP-E-BDT-T blends, which is the highest efficiency among small molecules based on DPP and BDT units. In active layer fabrication, 1,8-diiodooctane (DIO) was used as a solvent additive and subsequent thermal annealing treatment was also employed. We saw that these combined treatments led to balanced hole and electron transports, with values around 1.2 × 10−4 cm2 V−1 s−1 for the active layers. These results demonstrated that ethynylene bridges in small molecule donors are quite useful, both in tuning the electronic structure and in defining the thin film morphology, thus would be a promising method to enhance photovoltaic performances of the resulting materials.

Design, synthesis and photovoltaic properties of a series of new acceptor-pended conjugated polymers

Abstract: A series of novel acceptor-pended conjugated polymers featuring a newly developed carbazole-derived unit are designed and synthesized The relationships between chemical structure and optoelectronic properties of the polymers are systematically investigated The control of UV-Vis absorption spectra and energy levels in resulting polymers are achieved by introducing suitable pended acceptor units The photovoltaic properties of the resulting polymers are evaluated by blending the polymers with (6,6)-phenyl-C71-butyric acid methyl ester The resulting solar cells exhibit moderate performances with high open-circuit voltage Charge transport properties and morphology were investigated to understand the performance of corresponding solar cells

Synthesis and characterization of novel polymers containing aminophenylsilole

Abstract: 1,1-Bis(4′-N,N-dimethylaniline)-tetraphenylsilole (APh-TPS) and APh-TPS containing polymers (PF-APh-TPS) were successfully synthesized and characterized. Compared with the 1,1-dimethyl-2,3,4,5-tetraphenylsilole analogs, superior PLED performances were achieved based on PF-APh-TPS with 1,3,5-tris (2-N-phenylbenzimidazolyl) benzene (TPBI) as the hole-blocking layer.