DJL

Tuning of the energetic barriers to charge transfer at the semiconductor/dielectric interface in organic field-effect transistors (OFETs) is achieved by varying the dielectric functionality. Based on this, the correlation between the magnitude of the energy barrier and the gate-bias stress stability of the OFETs is demonstrated, and the origin of the excellent device stability of OFETs employing fluorinated dielectrics is revealed.

Freestanding, paper-like films of reduced graphene oxide (rGO) containing trace amounts of polymers are fabricated by an operationally simple, cost-effective, and environmentally friendly gel-film approach. The films, which can have a large area, display ultrahigh strengths and toughnesses as well as high electrical conductivities.

Honeycomb-like MoS₂ nanoarchitectures anchored into 3D graphene foam are successfully fabricated as a high-performance positive electrode for enhanced Li-ion storage. The unique 3D interpenetrating honeycomb-like structure is the key to the high performance. High reversible capacity, superior high-rate capability, and excellent cycling stability are demonstrated.

MoS₂ nanoflowers with expanded interlayer spacing of the (002) plane were synthesized and used as high-performance anode in Na-ion batteries. By controlling the cut-off voltage to the range of 0.4–3 V, an intercalation mechanism rather than a conversion reaction is taking place. The MoS₂ nanoflower electrode shows high discharge capacities of 350 mAh g⁻¹ at 0.05 A g⁻¹, 300 mAh g⁻¹ at 1 A g⁻¹, and 195 mAh g⁻¹ at 10 A g⁻¹. An initial capacity increase with cycling is caused by peeling off MoS₂ layers, which produces more active sites for Na⁺ storage. The stripping of MoS₂ layers occurring in charge/discharge cycling contributes to the enhanced kinetics and low energy barrier for the intercalation of Na⁺ ions. The electrochemical reaction is mainly controlled by the capacitive process, which facilitates the high-rate capability. Therefore, MoS₂ nanoflowers with expanded interlayers hold promise for rechargeable Na-ion batteries.

More active sites through peeling: MoS₂ nanoflowers with expanded interlayers were investigated as a high-performance anode material for Na-ion batteries. Excellent discharge capacities and high cycling stability were observed and were directly correlated with the expanded layer space and the decreased layer numbers.

A novel scheme for hybridizing inkjet-printed thin film Cu(In,Ga)Se₂ (CIGS) solar cells with self-assembled clusters of nanocrystal quantum dots (NQDs), which provides a 10.9% relative enhancement of the photon conversion efficiency (PCE), is demonstrated. A non-uniform layer of NQD aggregates is deposited between the transparent conductive oxide and a CdS/CIGS p-n junction using low cost pulsed-spray deposition. Hybridization significantly improves the external quantum efficiency of the hybrid devices in the absorption range of the NQDs and in the red to near-IR parts of the spectrum. The low wavelength response enhancement is found to be induced by luminescent down-shifting (LDS) from the NQD layer, while the increase at longer wavelengths is attributed to internal scattering from NQD aggregates. LDS is demonstrated using time-resolved spectroscopy, and the morphology of the NQD layer is investigated in fluorescence microscopy and cross-sectional transmission electron microscopy. The influence of the NQD dose on the PCE of the hybrid devices is investigated and an optimum value is obtained. The low costs and limited material consumptions associated with pulsed-spray deposition make these flexible hybrid devices promising candidates to help push thin-film photovoltaic technology towards grid parity.

Low-cost pulse-spray deposition is used to incorporate self-assembled clusters of luminescent nanocrystal quantum dots (NQDs) into a flexible thin-film Cu(In,Ga)Se₂ (CIGS) solar cell. Luminescent down-shifting and internal scattering on NQD clusters are found to provide a large broadband improvement of the quantum efficiency, yielding a 10.9% relative increase of the efficiency.