Performance improvement of an upconversion device through optimized carrier injection balance.

Enhancing carrier injection balance in near-infrared (NIR) to visible upconversion devices (UCDs) is crucial for improving efficiency and stability. This study presents the incorporation of an insulating polymer (polymethyl methacrylate (PMMA)) between an aluminum cathode and an electron transport layer to reduce excess electrons in a light-emitting layer, thus balancing electrode-injected electrons and NIR-generated holes. The optimized device achieved a fivefold increase in maximum luminance and upconversion efficiency compared to the control.

Universal Flexible Lamination Encapsulation Strategy toward Underwater-Operation Electroluminescence Devices.

A reliable encapsulation technology with scalability and flexibility is urgently needed for electroluminescence devices. Here, we developed a simple, robust, low-cost, and scalable flexible lamination encapsulation strategy with quantum-dot light-emitting diodes (QLEDs) as the model devices. Multilayered Parafilm combining with calcium oxide buffer was used for the lamination encapsulation.

Near-infrared and visible light dual-mode organic photodetectors.

We report a dual-mode organic photodetector (OPD) that has a trilayer visible light absorber/optical spacer/near-infrared (NIR) light absorber configuration. In the presence of NIR light, photocurrent is produced in the NIR light-absorbing layer due to the trap-assisted charge injection at the organic/cathode interface at a reverse bias. In the presence of visible light, photocurrent is produced in the visible light-absorbing layer, enabled by the trap-assisted charge injection at the anode/organic interface at a forward bias.

In situ investigation of energy transfer in hybrid organic/colloidal quantum dot light-emitting diodes via magneto-electroluminescence.

Energy transfer (ET) and charge injection (CI) in the hybrid organic/colloidal quantum dot light-emitting diodes (QD-LEDs) have been investigated by using magneto-electroluminescence (MEL) as an in situ tool. The feasibility and availability of MEL as an in situ tool were systematically demonstrated in the typical QD-LEDs based on CdSe-ZnS core-shell QDs. Our results suggest that the ET and CI processes can be well discerned by MEL measurements since these two processes exhibit distinct responses to the applied magnetic field.

Enhancing Crystalline Structural Orders of Polymer Semiconductors for Efficient Charge Transport via Polymer-Matrix-Mediated Molecular Self-Assembly.

A facile polymer-matrix-mediated molecular self-assembly of polymer semiconductors into highly crystalline orders for efficient charge transport in organic thin-film transistors is demonstrated. Phenomenal enhancements in field-effect mobility of about one order of magnitude and current on/off ratio of two to three orders of magnitude are realized with polyacrylonitrile-incorporated polymer semiconductor compositions via solution deposition.

Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors.

Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility.

High-Efficiency Phosphorescent Hybrid Organic-Inorganic Light-Emitting Diodes Using a Solution-Processed Small-Molecule Emissive Layer.

The morphology and optical and electrical properties of solution-processed and vacuum-deposited 4,4',4″-tris(carbazol-9-yl)triphenylamine (TCTA):2,2'-(1,3-phenylene)bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7) composite films are investigated. All of the films exhibit smooth and pinhole-free morphology, while the evaporated films possess enhanced carrier-transport properties compared to solution-processed ones. The close correlation between the carrier-transport feature and the packing density of the film is established.

Photocurrent generation through electron-exciton interaction at the organic semiconductor donor/acceptor interface.

In this work, we report our effort to understand the photocurrent generation that is contributed via electron-exciton interaction at the donor/acceptor interface in organic solar cells (OSCs). Donor/acceptor bi-layer heterojunction OSCs, of the indium tin oxide/copper phthalocyanine (CuPc)/fullerene (C60)/molybdenum oxide/Al type, were employed to study the mechanism of photocurrent generation due to the electron-exciton interaction, where CuPc and C60 are the donor and the acceptor, respectively. It is shown that the electron-exciton interaction and the exciton dissociation processes co-exist at the CuPc/C60 interface in OSCs.

Graphene quantum-dot-doped polypyrrole counter electrode for high-performance dye-sensitized solar cells.

Herein graphene quantum dot (GQD), a graphene material with lateral dimension less than 100 nm, is explored to dope PPy on F-doped tin oxide glass as an efficient counter electrode for high-performance dye-sensitized solar cells (DSSCs). The GQDs-doped PPy film has a porous structure in comparison to the densely structured plain PPy, and displays higher catalytic current density and lower charge transfer resistance than the latter toward I3(-)/I(-) redox reaction. The highest power conversion efficiency (5.