Optical Materials Express
Editor-in-Chief, Andrea
Alù, introduces new topic categories for the Journal that
redefine the Journal scope and better reflect the current state of
this dynamic field of ...research.
Discovering novel sulfate optical materials with strong second‐harmonic generation (SHG) and large birefringence is confronted by a great challenge attributed to the intrinsically weak polarizability ...and optical anisotropy of tetrahedral SO4 groups. Herein, two superior‐performing sulfate optical materials, namely, noncentrosymmetric Hg3O2SO4 and centrosymmetric CsHgClSO4 ⋅ H2O, have been successfully synthesized through the introduction of a highly polarizable d10 metal cation, Hg2+. The unique component layers in the reported compounds, Hg3O2SO4∞ layers in Hg3O2SO4 and HgClSO4(H2O)∞-
layers in CsHgClSO4 ⋅ H2O, induce enlarged birefringence in each sulfate. Remarkably, Hg3O2SO4 exhibits a very large SHG response (14 times that of KH2PO4), which is the strongest efficiency among all the reported nonlinear optical sulfates. Detailed theoretical calculations confirm that the employment of highly polarizable Hg2+ is an effective strategy to design superior optical materials with large birefringence and strong SHG response.
A HgII‐based sulfate NLO crystal, Hg3O2SO4, which achieves a perfect balance between SHG coefficient and birefringence, exhibits a giant SHG response (14 times that of KDP), as well as an appropriate birefringence (0.10@546 nm) attributable to the unique component Hg3O2SO4∞ layers.
The development of a data‐driven science paradigm is greatly revolutionizing the process of materials discovery. Particularly, exploring novel nonlinear optical (NLO) materials with the birefringent ...phase‐matching ability to deep‐ultraviolet (UV) region is of vital significance for the field of laser technologies. Herein, a target‐driven materials design framework combining high‐throughput calculations (HTC), crystal structure prediction, and interpretable machine learning (ML) is proposed to accelerate the discovery of deep‐UV NLO materials. Using a dataset generated from HTC, an ML regression model for predicting birefringence is developed for the first time, which exhibits a possibility of achieving fast and accurate prediction. Essentially, crystal structures are adopted as the only known input of this model to establish a close structure‐property relationship mapping birefringence. Utilizing the ML‐predicted birefringence which can affect the shortest phase‐matching wavelength, a full list of potential chemical compositions based on an efficient screening strategy is identified. Further, eight structures with good stability are discovered to show potential applications in the deep‐UV region, owing to their promising NLO‐related properties. This study provides a new insight into the discovery of NLO materials and this design framework can identify desired materials with high performances in the broad chemical space at a low computational cost.
A target‐driven materials design framework combining high‐throughput calculations, crystal structure prediction, and machine learning is proposed to accelerate the discovery of deep‐UV NLO materials. The machine learning regression model for predicting birefringence is developed for the first time. As an application, eight compounds with promising NLO‐related properties which show potential applications in the deep‐UV region are identified.
A series of fluorene‐based oligomers with novel spiro‐annulated triarylamine structures, namely DFSTPA, TFSTPA, and TFSDTC, are synthesized by a Suzuki cross‐coupling reaction. The ...spiro‐configuration molecular structures lead to very high glass transition temperatures (197–253 °C) and weak intermolecular interactions, and consequently the structures retain good morphological stability and high fluorescence quantum efficiencies(0.69–0.98). This molecular design simultaneously solves the spectral stability problems and hole‐injection and transport issues for fluorene‐based blue‐light‐emitting materials. Simple double‐layer electroluminescence (EL) devices with a configuration of ITO/TFSTPA (device A) or TFSDTC (device B)/ TPBI/LiF/Al, where TFSTPA and TFSDTC serve as hole‐transporting blue‐light‐emitting materials, show a deep‐blue emission with a peak around 432 nm, and CIE coordinates of (0.17, 0.12) for TFSTPA and (0.16, 0.07) for TFSDTC, respectively, which are very close to the National Television System Committee (NTSC) standard for blue (0.15, 0.07). The maximum current efficiency/external quantum efficiencies are 1.63 cd A−1/1.6% for device A and 1.91 cd A−1/2.7% for device B, respectively. In addition, a device with the structure ITO/DFSTPA/Alq3/LiF/Al, where DFSTPA acts as both the hole‐injection and ‐transporting material, is shown to achieve a good performance, with a maximum luminance of 14 047 cd m−2, and a maximum current efficiency of 5.56 cd A−1. These values are significantly higher than those of devices based on commonly usedN,N′‐di(1‐naphthyl)‐N,N′‐diphenyl‐1,1′‐biphenyl‐4,4′‐diamine (NPB) as the hole‐transporting layer (11 738 cd m−2 and 3.97 cd A−1) under identical device conditions.
A novel molecular design of fluorene‐based oligomers imparts these materials with excellent thermal stability, high fluorescence quantum efficiency, pronounced spectra stability, good hole injection, and excellent transporting ability. Deep‐blue‐light OLEDs based on these undoped fluorene‐based emitters (see figure) achieved good performance with maximum efficiencies up to 1.91 cd A−1 (external quantum efficiency of 2.7%). DFSTPA as a hole‐injection and transporting material greatly improves device performance as compared to the common NPB‐based device.
Deep‐ultraviolet nonlinear optical (DUV NLO) crystals are the key materials to extend the output range of solid‐state lasers to below 200 nm. The only practical material KBe2BO3F2 suffers high ...toxicity through beryllium and strong layered growth. Herein, we propose a beryllium‐free material design and synthesis strategy for DUV NLO materials. Introducing the (BO3F)4−, (BO2F2)3−, and (BOF3)2− groups in borates could break through the fixed 3D B–O network that would produce a larger birefringence without layering and simultaneously keep a short cutoff edge down to DUV. The theoretical and experimental studies on a series of fluorooxoborates confirm this strategy. Li2B6O9F2 is identified as a DUV NLO material with a large second harmonic generation efficiency (0.9×KDP) and a large predicted birefringence (0.07) without layering. This study provides a feasible way to break down the DUV wall for NLO materials.
Be gone: A strategy to prepare a beryllium‐free material that does not grow in layers for deep‐UV (DUV) nonlinear optical (NLO) materials is developed and carried out. Introducing the (BO3F)4−, (BO2F2)3−, and (BOF3)2− groups in borates is a feasible way to balance the criteria of deep‐UV NLO materials, breaking down the DUV wall for NLO materials.
Current nonlinear optical materials face a conventional limitation in the trade‐off between the band gap and birefringence, especially in the deep UV spectral region. To circumvent this dilemma, we ...propose a general principle, π‐conjugated confinement, to partially decouple the interunit π‐conjugated interactions by the separation of non‐π‐conjugated units. The goal is to further enlarge the band gap to a value larger than that of the singular π‐conjugated counterpart and to maintain a suitable density of π‐conjugated units to gain a large optical anisotropy. We reveal that π‐conjugated confinement is a shared structural feature for all DUV NLO materials known to date, and thus, it provides a novel and essential design criterion for future design synthesis. Guided by this principle, the carbonophosphates are predicted to be a new promising DUV candidate system. Sr3YPO4CO33 (1) and Na3XPO4CO3 (X=Ba, Sr, Ca, Mg, 2–5) exhibit not only greatly enhanced birefringence that is 3–24 times larger than that of singular phosphates but also enhanced band gaps that are 0.2–1.7 eV wider than those of singular carbonates.
We propose a general principle, π‐conjugated confinement, for the rational design of high‐performance DUV NLO materials whose band gaps are further enhanced. This principle is valid for all the DUV NLO materials known to date (the Chinese lunar year of the ox). Guided by this approach, the carbonophosphates are discovered for the first time as new DUV NLO candidates. Sr3YPO4CO33 exhibits the shortest SHG output laser among phosphates to date.
11.6%‐efficiency Cu2ZnSnSe4 (CZTSe) thin‐film solar cells are fabricated via a thermal co‐evaporation method. The CZTSe thin film with improved microstructure exhibits a minority carrier diffusion ...length over 2 μm, resulting in efficient photogenerated carrier collection in the device. A comparative study of photoluminescence in pure selenide and pure sulfide devices shows reduced band‐tailing for the pure selenide phase.
Abstract
In the twenty fisrt century Science and Technology (IPTEK) is developing very rapidly, including in the aspect of communication. This is closely related to everyday life because of the use ...of technology as a tool that makes human work easier. Long distance communication is commonplace in this era. Currently due to the COVID-19 pandemic, student learning is being carried out online using one of the online media, namely Google Meet. So with this technological advancement, learning can be done anywhere and anytime. The purpose of this study was to develop online lesson plan or lesson plans using the Project Based Learning (PjBL) learning model on optical materials. The method used is ADDIE (Analysis), Design (Design), Development (Development), Implementation (Implementation), and Evaluation (Evaluation). After going through the process of validation and testing on students, the results of the development of this learning device are valid so that they can be used
•Novel CYLP:Dy3+ white phosphors were synthesized firstly.•Crystal structure, morphology and phase composition were examined.•Detailed excitation and emission spectra property of CYLP:Dy3+ was ...studied.•Interaction mechanism between Dy3+ and their decay time were investigated.•Thermal quenching behavior and related mechanism were discussed in detail.
To explore novel single phase warm white light emitting phosphor, a series of phosphate phosphors Ca18Li3Y(PO4)14:Dy3+ were prepared. The phase purity, crystal structure, morphology and element component were confirmed by XRD Rietveld structure refinement, SEM and EDS analysis. The luminescence process of Ca18Li3Y(PO4)14:Dy3+ were systematically studied by photoluminescence spectroscopy and decay curves. The results indicated Ca18Li3Y(PO4)14:Dy3+ phosphors had strong excitation from 300 nm to 420 nm. Under the excitation of 350 nm, warm white light emission was achieved with the CIE color coordinates of (0.399, 0.448) and low CCT of ~ 3992 K. The concentration quenching mechanism and quantum efficiency of Dy3+ in Ca18Li3Y(PO4)14:Dy3+ were calculated and discussed in detail. The thermal quenching behavior revealed that Ca18Li3Y(PO4)14:Dy3+ had excellent thermal stability with stable color rendition. The thermal activation energy was finally calculated. All the results indicated the potential application of Ca18Li3Y(PO4)14:Dy3+ white light emission phosphor to be used in solid state lighting.
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