We present state-of-the-art first principles calculations for the IV characteristics of a donor-insulator-acceptor (DsigmaA) type molecular diode anchored with thiolate bonds to two gold electrodes. We find very poor diode characteristics of the device, and the origin of this is analyzed in terms of the bias-dependent electronic structure. At zero bias, the highest occupied molecular orbital (HOMO) is confined to the D part, and the lowest unoccupied molecular orbital (LUMO) is confined to the A part, while at 3.8 V the two states align, and this gives rise to an increasing current. The latter is a potential mechanism for rectification and may in some cases lead to favorable diode characteristics. We identify the origin of the vanishing rectification for the investigated molecule, and on the basis of this we suggest parameters which are important for successful chemical engineering of DsigmaA rectifiers.
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http://dx.doi.org/10.1021/ja028229x | DOI Listing |
ACS Appl Mater Interfaces
January 2025
School of Materials Science and Engineering, Kyungpook National University, Daegu 41566, Republic of Korea.
The development of quantum dot light-emitting diodes (QLEDs) represents a promising advancement in next-generation display technology. However, there are challenges, especially in achieving efficient hole injection, maintaining charge balance, and replacing low-stability organic materials such as PEDOT:PSS. To address these issues, in this study, self-assembled monolayers (SAMs) were employed to modify the surface properties of NiO, a hole injection material, within the structure of ITO/HIL/TFB/QDs/ZnMgO/Al QLEDs.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
University of Science and Technology of China, Chemistry and Material Science, No.96, JinZhai Road Baohe District, 230026, Hefei, CHINA.
Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials have great potential for applications in ultrahigh-definition (UHD) organic light-emitting diode (OLED) displays, that benefit from their narrowband emission characteristic. However, key challenges such as aggregation-caused quenching (ACQ) effect and slow triplet-to-singlet spin-flip process, especially for blue MR-TADF materials, continue to impede their development due to planar skeletons and relatively large ΔESTs. Here, an effective strategy that incorporates multiple carbazole donors into the parent MR moieties is proposed, synergistically engineering their excited states and steric hindrances to enhance both the spin-flip process and quenching resistance.
View Article and Find Full Text PDFNanoscale
January 2025
The Canter for Photochemical Sciences and Department of Physics, Bowling Green State University, Bowling Green, Ohio 43403, USA.
Laser diodes based on solution-processed semiconductor quantum dots (QDs) present an economical and color-tunable alternative to traditional epitaxial lasers. However, their efficiency is significantly limited by non-radiative Auger recombination, a process that increases lasing thresholds and diminishes device longevity through excessive heat generation. Recent advancements indicate that these limitations can be mitigated by employing spherical quantum wells, or quantum shells (QSs), in place of conventional QDs.
View Article and Find Full Text PDFMicromachines (Basel)
November 2024
State Key Discipline Laboratory of Wide Band-Gap Semiconductor Technology, School of Microelectronics, Xidian University, Xi'an 710071, China.
In this work, we show a high-performance GaN-on-Si quasi-vertical PiN diode based on the combination of beveled sidewall and fluorine plasma treatment (BSFP) by an inductively coupled plasma (ICP) system. The leakage current and breakdown voltage of the diode are systematically studied. Due to the beveled sidewall treated by the fluorine plasma, the diodes achieve an excellent breakdown voltage (V) of 790 V and a low reverse leakage current.
View Article and Find Full Text PDFEntropy (Basel)
December 2024
Department of Engineering, University of Campania "Luigi Vanvitelli", Via Roma 29, 81031 Aversa, Italy.
We present an experimental and numerical study of a piezoelectric energy harvester driven by broadband vibrations. This device can extract power from random fluctuations and can be described by a stochastic model, based on an underdamped Langevin equation with white noise, which mimics the dynamics of the piezoelectric material. A crucial point in the modelisation is represented by the appropriate description of the coupled load circuit that is necessary to harvest electrical energy.
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