The regioregular p-type copolymer PBDTTT-C-T comprised of TT-BDT-TT-BDT repeating units (TT = thieno[3,thiophene, BDT = benzo[1,2-b:4,5-b']dithoiphene) and perfectly controlled TT orientation was synthesized. The optical, thermal, and electrochemical properties of the reigoreular PBDTTT-C-T were characterized and compared with the random PBDTTT-C-T without structural regioreguarity. The regioregular PBDTTT-C-T showed lower optical bandgap (1.55 eV) and higher degree of crystallinity compared to the random PBDTTT-C-T. The inverted bulk heterojunction PSCs based on the regioregular PBDTTT-C-T exhibited a power conversion efficiency as high as 7.79%, which is 19% higher than the random PBDTTT-C-T based PSCs. It was found that the improved photoabsorption and increase in charge carrier mobility due to high regioegulartity of conjugated polymer backbones and effective ordering between polymer chains are the most likely reasons for enhancement of power conversion efficiency in PSCs.

Conventional printing technologies such as inkjet, screen, and gravure printing have been used to fabricate patterns of silver nanowire (AgNW) transparent conducting electrodes (TCEs) for a variety of electronic devices. However, they have critical limitations in achieving micrometer-scale fine line width, uniform thickness, sharp line edge, and pattering of various shapes. Moreover, the optical and electrical properties of printed AgNW patterns do not satisfy the performance required by flexible integrated electronic devices. Here, we report a high-resolution and large-area patterning of highly conductive AgNW TCEs by reverse offset printing and intense pulsed light (IPL) irradiation for flexible integrated electronic devices. A conductive AgNW ink for reverse offset printing is prepared by carefully adjusting the composition of AgNW content, solvents, surface energy modifiers, and organic binders for the first time. High-quality and highresolution AgNW micropatterns with various shapes and line widths are successfully achieved on a large-area plastic substrate (120 × 100 mm 2 ) by optimizing the process parameters of reverse offset printing. The reverse offset printed AgNW micropatterns exhibit superior fine line widths (up to 6 μm) and excellent pattern quality such as sharp line edge, fine line spacing, effective wire junction connection, and smooth film roughness. They are post-processed with IPL irradiation, thereby realizing excellent optical, electrical, and mechanical properties. Furthermore, flexible OLEDs and heaters based on reverse offset printed AgNW micropatterns are successfully fabricated and characterized, demonstrating the potential use of the reverse offset printing for the conductive AgNW ink.

A regioregular D1-A-D2-A terpolymer PDTST­TBDT incorporating dithieno­[3,2-b:2′,3′-d]­silole (DTS, D1) and benzo­[1,2-b:4,5-b]­dithiophene (BDT, D2) units with perfectly controlled thieno­[3,4-b]­thiophene (TT, A) orientation was synthesized for the first time. The thermal, optical, and electrochemical properties of the regioregular PDTSTTBDT were characterized and compared with the random PDTSTTBDT without structural regioregularity. The regioregular PDTSTTBDT showed ideal optical bandgap (1.45 eV), lower lying HOMO energy level, and higher degree of crystallinity compared to the random PDTST­TBDT. Moreover, it exhibited excellent solubility in nonhalogenated solvents as well as halogenated solvents. The inverted bulk-heterojunction polymer solar cells (PSCs) based on the regioregular PDTST­TBDT and o-xylene process solvent showed a power conversion efficiency as high as 6.14%, which is 500% higher than the random PDTST­TBDT-based PSCs. It was found that the remarkable enhancement of photovoltaic performance in regioregular PDTST­TBDT-based PSCs is mainly due to improved light absorption, effective polymer ordering, and high charge carrier mobility.

High-performance transparent pressure sensors have been successfully fabricated using sea-urchin shaped metal nanoparticles and polyurethane microdome arrays for real-time monitoring.

We synthesized and characterized two kinds of regioregular polymers that were based on thieno [3,4-b]thiophene as an electron-accepting unit and benzo [1,2-b:4,5-b′]dithiophene as the electron-donating unit with different side chain, alkylthio and alkyl thiophenes, named rr-PTBS and rr-PTB7-Th, respectively. Because of the partial introduction of the alkylthio thiophene side chain, rr-PTBS showed red-shifted absorption and a deeper HOMO level compared to those of rr-PTB7-Th. In addition, both rr-PTBS:PC 71 BM and rr-PTB7-Th:PC 71 BM blended films showed face-on orientations stronger than those of regiorandom PTB7-Th. However, the rr-PTB7-Th:PC 71 BM blended film showed a peak in the outof-plane direction much weaker than those of rr-PTBS:PC 71 BM and PTB7-Th:PC 71 BM blended films. Moreover, the rr-PTBS:PC 71 BM blended film exhibited charge carrier mobility (μ e /μ h ∼ 1.01) much more balanced than that of the rr-PTB7-Th:PC 71 BM blended film (μ e /μ h ∼ 1.23). The bulkheterojunction organic photovoltaic (OPV) device based on rr-PTBS and the 1,8-diiodooctane additive showed a high power conversion efficiency (PCE) of 8.68%, while the OPV device based on rr-PTB7-Th and the 1,8-diiodooctane additive showed a PCE of 7.04%. Finally, an OPV device using rr-PTBS, the diphenyl ether additive, and Micro Lens Film exhibited a short-circuit current (J sc ) of 19.72 mA/cm 2 , an open-circuit voltage (V oc ) of 0.82 V, and a fill factor (FF) of 63.82%, thus resulting in a PCE of 10.31%.