Semitransparent organic photovoltaics (ST‐OPVs) have great potential for use in renewable energy technologies. In bulk‐heterojunction (BHJ) ST‐OPVs, a compromise is necessary between the visible ...light transmittance (VLT) and the power conversion efficiency (PCE). A sequential deposition (SD) strategy that involves individually depositing a polymer donor layer (D) and a small‐molecule acceptor layer (A) as the active layer is presented; where molecular diffusion occurring at the interfacial region results in a pseudo p–i–n structure. PBDB‐T‐2F(D)/Y6(A) ST‐OPVs are fabricated with different active layer thicknesses—at 115 nm, the SD (D:A/75:40 nm) and BHJ devices (D:A/1:1.2 w) provide the champion PCE of 12.91% (VLT of 14.5%) and 12.77% (VLT of 13.4%), respectively; at 85 nm, the SD (D:A/45:40 nm) and BHJ devices (D:A/1:1.2 w) provide a PCE of 12.22% (VLT of 22.2%) and 11.23% (VLT of 16.6%), respectively. This trend indicates SD devices have larger PCE and VLT values than the BHJ devices at a given active layer thickness, and the enhancements of PCE and VLT values by the SD structures against the BHJ structures become more pronounced as the active layer thickness reduced. The SD strategy provides a new approach for achieving ST‐OPVs with both high efficiency and high transparency.
In typical semitransparent organic photovoltaics (ST‐OPVs) that incorporate bulk heterojunction (BHJ) active layers, a compromise is made between the visible light transmittance (VLT) and power conversion efficiency (PCE). A new strategy with a sequential‐deposition (SD) active layer involving pseudo p–i–n structures provides ST‐OPVs with simultaneously higher PCE and VLT than that of the BHJ devices at the same layer thickness.
The phosphor‐converted light‐emitting diode (PC‐LED) has become an indispensable solid‐state lighting and display technologies in the modern society. Nevertheless, the use of scarce rare‐earth ...elements and the thermal quenching (TQ) behavior are still two most crucial issues yet to be solved. Here, this work successfully demonstrates a highly efficient and thermally stable green emissive MnI2(XanPO) crystals showing a notable photoluminescence quantum yield (PLQY) of 94% and a super TQ resistance from 4 to 623 K. This unprecedented superior thermal stability is attributed to the low electron–phonon coupling and the unique rigid crystal structure of MnI2(XanPO) over the whole temperature range based on the temperature‐dependent photoluminescence (PL) and single crystal X‐ray diffraction (SCXRD) analyses. Considering these appealing properties, green PC‐LEDs with a power efficacy of 102.5 lm W−1, an external quantum efficiency (EQE) of 22.7% and a peak luminance up to 7750 000 cd m−2 are fabricated by integrating MnI2(XanPO) with commercial blue LEDs. Moreover, the applicability of MnI2(XanPO) in both micro‐LEDs and organic light‐emitting diodes (OLEDs) is also demonstrated. In a nutshell, this study uncovers a candidate of highly luminescent and TQ resistant manganese halide suitable for a variety of emission applications.
A highly efficient and thermally stable manganese halide crystal, MnI2(XanPO) is demonstrated. The low electron–phono coupling along with rigid crystal structure contributes to excellent photoluminescent quantum yield of 94% with unprecedented near zero thermal quenching from 4 to 623 K. The crystals find their applications in light emitting diodes and micro light emitting diodes with excellent external quantum efficiency (EQE) up to 22.7% and power efficacy as high as 102.5 lm W−1.
Micro-light-emitting diodes (μLEDs) are getting much attention in display industry because of their outstanding optical and electrical characteristics. μLEDs have several advantages over liquid ...crystal displays (LCDs) and organic light-emitting diodes (OLEDs). μLEDs are showing long lifetimes, high reliability, high power efficiencies, high brightness, and fast response times with tiny pixels. However, for commercial usage, the high production cost and low external quantum efficiency (EQE) are the major hurdles. In this review, we briefly discuss the breakthroughs in μLED technology, fabrication methods, optical/electrical characteristics, and challenges for display applications. In addition, the development of monolithic μLEDs and general device characteristics combined with various quantum dot patterning processes are systematically discussed. Potential solutions to address these challenges are also presented case by case.
A bolt from the blue? Compounds like that shown containing benzimidazole and arylamine units exhibit intriguing ambipolar carrier‐transport properties and can be used to fabricate single‐layer ...blue‐emitting electroluminescent devices with very promising performances (see picture, ITO=indium tin oxide).
A series of compounds containing arylamine and 1,2‐diphenyl‐1H‐benzdimidazole moieties are developed as ambipolar, blue‐emitting materials with tunable blue‐emitting wavelengths, tunable ambipolar ...carrier‐transport properties and tunable triplet energy gaps. These compounds possess several novel properties: (1) they emit in the blue region with high quantum yields; (2) they have high morphological stability and thermal stability; (3) they are capable of ambipolar carrier transport; (4) they possess tunable triplet energy gaps, suitable as hosts for yellow‐orange to green phosphors. The electron and hole mobilities of these compounds lie in the range of 0.68–144 × 10−6 and 0.34–147 × 10−6 cm2 V−1 s−1, respectively. High‐performance, single‐layer, blue‐emitting, fluorescent organic light‐emitting diodes (OLEDs) are achieved with these ambipolar materials. High‐performance, single‐layer, phosphorescent OLEDs with yellow‐orange to green emission are also been demonstrated using these ambipolar materials, which have different triplet energy gaps as the host for yellow‐orange‐emitting to green‐emitting iridium complexes. When these ambipolar, blue‐emitting materials are lightly doped with a yellow‐orange‐emitting iridium complex, white organic light‐emitting diodes (WOLEDs) can be achieved, as well by the use of the incomplete energy transfer between the host and the dopant.
High‐performance, single‐layer, blue, fluorescent OLEDs based on ambipolartransport compounds containing arylamine and 1,2‐diphenyl‐1H‐benzdimidazole moieties are described. High‐performance yellow‐orange and green, single‐layer, phosphorescent OLEDs are also possible by using these materials as the host for phosphorescent dopants. White OLEDs can also be achieved.
•Cu, Ni and Ti significantly enhanced the corrosion resistance of the spring steel.•The formation and expansion of corrosion pits and its transformation mechanism to uniform corrosion were ...revealed.•Ti improved the resistance to hydrogen-induced fracture of the high-strength spring-steel.
The disadvantages of poor corrosion resistance and delayed fracture resistance of high-strength medium-carbon spring steel have significantly limited its application in the construction industry. Therefore, there is a need to improve these characteristics of spring steel. In this paper, the effects of Ti, Cu, and Ni on the microstructure, mechanical properties, corrosion resistance, and hydrogen-induced delayed fracture behaviour of spring steel were investigated by scanning electron microscopy, transmission electron microscopy, electrochemical workstation analysis, neutral salt spray test and hydrogen permeation testing methods. The results showed that the tensile strength of the experimental steel reached 2000 MPa and the yield strength reached 1800 MPa. These values were observed when the quenching and tempering temperatures were 900 °C and 350 °C, respectively; further, the experimental steel had a tempered martensite microstructure at these temperatures. Ti increased the self-corrosion potential of the experimental steel and reduced the self-corrosion current. With an increase in the content of alloying elements (Ti, Cu, and Ni), the depth of the corrosion pits in the experimental steel became shallower and the degree of surface damage was reduced. Moreover, Ti could refine the crystal grains, TiC had high a trap activation energy of hydrogen, and Ti-containing steel had better hydrogen-induced fracture resistance.
Perovskite materials prepared in the form of solution-processed nanocrystals and used in top-down fabrication techniques are very attractive to develop low-cost and high-quality integrated ...optoelectronic circuits. Particularly, integrated miniaturized coherent light sources that can be connected to light-guiding structures on a chip are highly desired. To control light propagating on a small footprint with low-loss optical modes, long-range surface plasmon polariton (LRSPP) waveguides are employed. Herein, we demonstrate an on-chip fabricated photonic-plasmonic hybrid system consisting of a perovskite lasing structure coupled to an LRSPP waveguide achieving a low lasing threshold and a propagation length over 100 μm. Preventing perovskite material degradation and the formation of surface roughness of the laser cavity during fabrication is made possible by designing a fabrication technique without any etching step.
The coupling of on-chip perovskite nanocrystal lasers and the long-range surface plasmon polariton (LRSPP) waveguides is demonstrated with an etching-free lithographic patterning technique.
In this research work, the gas sensing properties of halogenated chloroaluminum phthalocyanine (ClAlPc) thin films were studied at room temperature. We fabricated an air-stable ClAlPc gas sensor ...based on a vertical organic diode (VOD) with a porous top electrode by the solution process method. The surface morphology of the solution-processed ClAlPc thin film was examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The proposed ClAlPc-based VOD sensor can detect ammonia (NH
) gas at the ppb level (100~1000 ppb) at room temperature. Additionally, the ClAlPc sensor was highly selective towards NH
gas compared to other interfering gases (NO
, ACE, NO, H
S, and CO). In addition, the device lifetime was tested by storing the device at ambient conditions. The effect of relative humidity (RH) on the ClAlPc NH
gas sensor was also explored. The aim of this study is to extend these findings on halogenated phthalocyanine-based materials to practical electronic nose applications in the future.
We demonstrate semipolar (20-21) micro-LED-based high-bandwidth WLEDs utilizing perovskite QDs and organic emitters in color-conversion films. The WLEDs exhibit a bandwidth in excess of 1 GHz and a ...CCT of 6141 K, making these devices suitable for visible light communication and lighting applications.
Pictorial representation of high-bandwidth WLEDs by utilizing combinations of perovskite quantum dots (PQDs) and organic materials as color converters under the excitation of a semipolar blue micro-LED.
The solar cell has a poor spectral response in the UV region, which affects its power conversion efficiency (PCE). The utilization of a luminescent downshifting (LDS) layer has been suggested to ...improve the spectral response of the photovoltaics in the short wavelength region through photoluminescence (PL) conversion and antireflection effects, which then enhance the PCE of the solar cell. Recently, colloidal quantum dots (CQDs) or perovskite quantum dots (PQDs) have been gaining prime importance as an LDS material due to their eminent optical characteristics, such as their wide absorption band, adjustable visible emission, short PL lifetime, and near-unity quantum yields. However, the instability of QDs that occurs under certain air, heat, and moisture conditions limits its commercialization. Thus, in this review, we will focus on the physical and optical characteristics of QDs. Further, we will discuss different synthesis approaches and the stability issues of QDs. Different approaches to improve the stability of QDs will be discussed in detail alongside the recent breakthroughs in QD-based solar cells for various applications and their current challenges. We expect that this review will provide an effective gateway for researchers to fabricate LDS-layer-based solar cells.
PDF
