Search

A highly efficient fullerene-free polymer solar cell (PSC) based on PDCBT, a polythiophene derivative substituted with alkoxycarbonyl, achieves an impressive power conversion efficiency of 10.16%, which is the best result in PSCs based on polythiophene derivatives to date. In comparison with a poly(3-hexylthiophene):ITIC-based device, the photovoltaic and morphological properties of the PDCBT:ITIC-based device are carefully investigated and interpreted.

A well-organized donor-acceptor crystalline structure is examined for high -performance nonfullerene solar cells. By thermal annealing, nanoscale structures of both donor and acceptor domains are successfully modulated, followed by -significant changes in the resulting -photovoltaic characteristics. When annealed at 90 °C, a maximum power conversion efficiency of 7.64% with a -remarkable open-circuit voltage of 1.03 V is obtained.

A series of difluorobenzoxadiazole-based copolymers are synthesized for applications in high-performance organic thin-film transistors. Four π-spacers with distinct electrical properties, bithiophene, difluorobithiophene, 2-thiophene-2′-thiazole, and bithiazole, are inserted between head-to-head linkage containing bithiophene to promote polymer chain packing. Among the series, polymer containing bithiophene exhibits a unipolar p-channel performance with a substantial hole mobility of 2.92 cm2 V−1 s−1, and minor structural modification leads to polymer containing bithiazole showing a remarkable unipolar n-channel performance with an electron mobility of 0.83 cm2 V−1 s−1. Through a simple structural modification, such a drastic charge carrier polarity change without sacrificing mobility is elusive in organic thin-film transistor field. Polymer containing hybrid 2-thiophene-2′-thiazole spacer exhibits ambipolarity with encouraging hole/electron mobility of 0.27/0.35 cm2 V−1 s−1, and polymer containing difluorobithiophene shows an average hole mobility of 0.53 cm2 V−1 s−1. Among the results, p-channel transistors exhibit encouraging device stability. The results demonstrate that difluorobenzoxadiazole is a versatile building block for enabling high-mobility semiconductors with variable charge carrier polarity. X-ray diffraction reveals that all difluorobenzoxadiazole-based polymers have substantial film crystallinity with close π-stacking and varied polymer chain orientation. The structure–property–device performance correlations from this study offer useful insights for materials innovation in organic thin-film transistors.

This study demonstrates high-performance, ternary-blend polymer solar cells by modifying a binary blend bulk heterojunction (PPDT2FBT:PC71BM) with the addition of a ternary component, PPDT2CNBT. PPDT2CNBT is designed to have complementary absorption and deeper frontier energy levels compared to PPDT2FBT, while being based on the same polymeric backbone. A power conversion efficiency of 9.46% is achieved via improvements in both short-circuit current density (JSC) and open-circuit voltage (VOC). Interestingly, the VOC increases with increasing the PPDT2CNBT content in ternary blends. In-depth studies using ultraviolet photoelectron spectroscopy and transient absorption spectroscopy indicate that the two polymers are not electronically homogeneous and function as discrete light harvesting species. The structural similarity between PPDT2CNBT and PPDT2FBT allows the merits of a ternary system to be fully utilized to enhance both JSC and VOC without detriment to fill-factor via minimized disruption of semi-crystalline morphology of binary PPDT2FBT:PC71BM blend. Further, by careful analysis, charge carrier transport in this ternary blend is clearly verified to follow parallel-like behavior.

Oxidative degradation of Brilliant Red X–3B has been carried out using Fenton’s reagent both in the dark and in the presence of visible light. The degradation rate was increased using Fenton’s process in the order of Dark < Visible < UV. At pH 3.3, the maximum Fenton and photo-Fenton effect were noticed. At [H2O2]/[Fe(III)] = 3.5, a steady Fenton effect was observed. Meanwhile, at [H2O2]/[Fe(III)] = 0.7, Fenton process in the dark minimized the photo effect. The degradation rate was positively influenced by the temperature where the activation energy of degradation was evaluated as 36.98 kJ mol-1.