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A new dicarbazole-based donor, BCz3Ph, for exciplex formation was synthesized and characterized. The new green (PL λmax = 527 nm) exciplex BCz3Ph : PO-T2T (2 : 1) blend with a photoluminescence quantum yield (PLQY) of 43% and thermally activated delayed fluorescence (TADF) character was utilized as the emitting layer (EML) of solution-processed OLED devices. To facilitate hole injection into the EML, a new cross-linkable monomer, BCzC4Sy, adopting a dicarbazole core linked to a styrene group by a butyl chain was designed to realize a solvent resistant hole-transporting layer (HTL) after thermal polymerization. The flexible butyl (C4) bridge accounts for a lower polymerization temperature as compared to that of the methyl (C1)-bridged counterpart, BCzC1Sy, resulting in the formation of amorphous films with better solvent resistance as well as smoother morphology. The choice of dicarbazole as the HTL core not only suppresses the HTL-to-EML energy barrier, but also prevents the emission color variation stemming from the possible exciplex emission at the HTL/EML interface. The best OLED device with EQEmax = 9.2%, CEmax = 27.94 cd A−1 and PEmax = 28.7 lm W−1 was obtained with a thermally polymerized BCzC4Sy film as the HTL. The device achieved a maximum luminance up to 22 000 cd m−2 together with a very low efficiency roll-off, retaining 97% efficiency at 1000 cd m−2 (EQE1000cd = 8.9%). More significantly, a 2 × 2 cm2 device fabricated by slot-die coating gave good color homogeneity and rather high brightness and promising efficiency (EQE 5.0%), manifesting the potential of employing a thermally cross-linkable HTM and exciplex-based EML to produce high efficiency solution-processed OLEDs. [ABSTRACT FROM AUTHOR]

This paper reports on a solvothermal method used in the fabrication of vertically aligned two-dimensional (2D) ZnO nanowall networks and one-dimensional (1D) ZnO nanorods with overlapping structures. The introduction of an Al thin film as a doping source was shown to alter the morphology from rods to walls. The proposed multilayer buffer results in the formation of two types of nanostructure (nanowalls and rods) and also increased the length to which the nanorods grow at the same time. Analysis based on transmission electron microscopy (TEM) and selected area electron diffraction (SAED) led us to formulate a possible growth mechanism and elucidate the optical properties of the ZnO nanostructures. [ABSTRACT FROM AUTHOR]

A two-step, spin-coating process to synthesize a high quality perovskite film at room temperature at ambient atmosphere is reported. Combining an optimized PEDOT:PSS hole-transport layer and a PC71BM acceptor, the device achieved a power conversion efficiency of 16.31% with a remarkably high Voc of 1.05 V and FF of 0.78. The efficiency reproducibility of the devices is also high: 80% of devices achieve efficiency higher than 15%. [ABSTRACT FROM AUTHOR]

This paper reports an inverted solar cell with ZnO nanorods for electron collection. Because ZnO materials could function as the electron transport layer in inverted organic solar cells, the ZnO nanorods further provided a large number of carrier extraction channels deep inside the organic active layer to improve carrier collection efficiency. The relationship between the ZnO nanorod array morphology and the device performance was systematically studied. Different ZnO nanorod morphologies could be controlled by the ratio of zinc nitrate and hexamethylenetetramine in a low-cost hydrothermal method, including the average spacing between individual nanorods and the surface area. For a maximum organic–inorganic contact area and good polymer infiltration, the morphology of the ZnO nanorod array has been optimized. When the ratio of zinc nitrate and hexamethylenetetramine was controlled at 1.0 : 0.6 in the growth-promoting solution, the surface area of the nanorod array was 7.55 times more than a planar ZnO structure. The ZnO nanorods significantly enhanced the performance of inverted PBDTTT-C-T:PC71BM solar cells and the power conversion efficiency of the device increased from 5.22% to 7.26%. [ABSTRACT FROM AUTHOR]