A high-performance hybrid white organic light-emitting device (WOLED) is demonstrated based on an efficient novel thermally activated delayed fluorescence (TADF) blue exciplex system. This device shows a low turn-on voltage of 2.5 V and maximum forward-viewing external quantum efficiency of 25.5%, which opens a new avenue for achieving high-performance hybrid WOLEDs with simple structures.

We report our effort to unravel the origin of efficient operation of nonfullerene organic solar cells (OSCs), based on a poly[4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)](PTB7-Th):3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno [1,2-b:5,6-b']dithiophene (ITIC) blend system. The effects of buildup of space charges, charge extraction, and bimolecular recombination processes on the performance and the stability of PTB7-Th:ITIC-based regular and reverse configuration OSCs are analyzed. It is found that the high-performing inverted PTB7-Th:ITIC OSCs benefit from the combined effects of (1) suppression of bimolecular recombination enabled by an augmented effective internal electric field and (2) improvement of charge extraction by avoiding the holes passing through ITIC-rich region, which would otherwise occur in a regular configuration cell. The inverted PTB7-Th:ITIC OSCs possess a significant improvement in the cell stability and a high power conversion efficiency of ∼8.0%, which is >29% higher than that of an optimized regular configuration control cell (6.1%).

Coexistence of negative differential resistance (NDR) and resistive switching (RS) memory is observed using a Ag|TiOx|F‐doped‐SnO2 memory cell at room temperature. Unlike other reports, the coexistence of NDR and RS strongly depends on the relative humidity levels at room temperature. The NDR disappears when the cells are placed in a dry air ambient (H2O < 5 ppm) or in vacuum, but the coexistence emerges and gradually becomes obvious after the cells are exposed to ambient air with relative humidity of 35%, and then becomes dramatically enhanced as the relative humidity becomes higher. Due to the excellent stability and reversibility of the coexistence of NDR and RS, a multilevel RS memory is developed at room temperature. Hydroxide ion (OH−) is induced by gas‐phase water‐molecule splitting on the surface and interface of the memory cell. The OH− interacts with oxygen vacancies and transports in the bulk of memory cell to facilitate the migration of Ag ions and oxygen vacancies along grain boundaries. These processes are responsible for the moisture‐modulated and room‐temperature coexistence. This work demonstrates moisture‐modulated coexistence of NDR and RS for the first time and gives an insight into the influence of water molecules on transition‐metal‐oxide‐based RS memory systems.

Organic solar cells (OSCs) with inverted structure usually exhibit higher power conversion efficiency (PCE) and are more stable than corresponding devices with regular configuration. Indium tin oxide (ITO) surface is often modified with solution-processed low work function metal oxides, such as ZnO, serving as the transparent cathode. However, the defect-induced subgap states in the ZnO interlayer hamper the efficient charge collection and the performance reproducibility of the OSCs. In this work, we demonstrate that suppression of the ZnO subgap states by modification of its surface with an ultrathin Al layer significantly improves the charge extraction and performance reproducibility, achieving PCE of 8.0%, which is ∼15% higher than that of a structurally identical control cell made with a pristine ZnO interlayer. Light intensity-dependent current density-voltage characteristic, photothermal deflection spectroscopy, and X-ray photoelectron spectroscopy measurements point out the enhancement of charge collection efficiency at the organic/cathode interface, due to the suppression of the subgap states in the ZnO interlayer.

The negative photoconductance (NPC) effect, defined as an increase in resistance upon exposure to illumination, holds great potential for application in photoelectric devices. A prepared memristor with the structure of Ag|graphene quantum dots (GQDs)|TiO x |F-doped SnO 2 exhibits typical bipolar resistive switching (RS) memory behavior. The NPC effect is impressively observed in the high resistance state branch of the RS memory, enabling the memristor function to be extended to both memory logic display and multistate data storage. The observed NPC effect is attributed to the excitation, migration, and compensation of oxygen vacancy at the GQDs/TiO x interface, at which the electron transportation is efficiently restricted because of the variation in the charge distribution and electrostatic potential under illumination. Experiments, theoretical calculations, and physical models are used to provide engineer the interface with the aim of building the NPC effect in the memristive device. These results unveil a new horizon on extending the functionality of the memristor.The memristor, which is the resistance switches, [1] is an emerging electronic device, whose internal conductance states depend on the history of the electrons and/or the ions it has experienced. [2][3][4][5][6] The programmable conductance states make it