One of society’s grand challenges is to reduce energy usage in ways that are cost-effective, sustainable, and environmentally benign. Replacing incandescent and compact fluorescent light bulbs with energy-efficient, solid-state white lighting is one of the easiest and most promising solutions. Eu3+-substituted inorganic oxide phosphors are one class of materials that can serve as the red component in these new light bulbs, allowing the creation of warm white light. Unfortunately, the emission intensity in most of these materials cannot be reliably maintained at elevated temperatures. There is therefore a need to discover entirely novel phosphor materials that are thermally robust; however, this is generally a prolonged and expensive process requiring extensive synthetic effort. In this work, we develop a machine-learning regression algorithm based on 134 experimentally measured temperature-dependent Eu3+ emission data points to rapidly estimate the thermal quenching temperature (T 50), which is defined as the temperature when the emission intensity is half of the initial value. The T 50 was then predicted for more than 1000 potential oxide Eu3+ phosphor hosts using this model. Five compounds with predicted thermal quenching temperatures >423 K were subsequently selected and synthesized for validation of this approach. The phosphors, Sr2ScO3F, Cs2MgSi5O12, Ba2P2O7, LiBaB9O15, and Y3Al5O12, all exhibit good thermal stability when substituted with Eu3+, suggesting the success of our methodology.

Cesium zinc silicate substituted with Eu 2+ has been synthesized as a new green-emitting phosphor with potential application in UV-based solid state white lighting. Cs 2 ZnSi 5 O 12 has been known to exhibit polymorphism, crystallizing in space group Pbca as well as Pa 3, as a structural analog to the cubic leucite, CsAlSi 2 O 6 . Using laboratory X-ray powder diffraction and optical spectroscopy, the crystal structure of Cs 2 ZnSi 5 O 12 :Eu 2+ , when prepared using high-temperature ceramic synthesis, was confirmed to adopt space group Pa 3. This novel phosphor produces a broad green emission (λ em = 504 nm) upon UV excitation. Encapsulating the compound in optically transparent silicone resin along with the red-emitting Sr 2 Si 5 N 8 :Eu 2+ and exciting with a UV-LED (λ ex = 370 nm) produces a warm white light with excellent color rendering. The advantage of developing a light using Cs 2 ZnSi 5 O 12 :Eu 2+ is that the broad green emission negates the need for incorporating three different phosphors as is commonly required for UV-pumping. This dramatically simplifies device design while still achieving high-quality UV-based white light. Once the emission efficiency and thermal stability of Cs 2 ZnSi 5 O 12 :Eu 2+ is improved, there can be seamless integration with UV-LEDs for high-quality warm white light production.

The template-free unidirectional alignment of lamellar block copolymers (l-BCPs) for sub-10 nm high-resolution patterning and hybrid multicomponent nanostructures is important for technological applications. We demonstrate a modified soft-shear-directed self-assembly (SDSA) approach for aligning pristine l-BCPs and l-BCPs with incorporated polymer-grafted nanoparticles (PGNPs), as well as the l-BCP conversion to aligned gold nanowires, and hybrid of metallic gold nanowire and dielectric silica nanoparticle in the form of line-dot nanostructures. The smallest patterns have a half-pitch as small as 9.8 nm. In all cases, soft-shear is achieved using a high-molecular-mass polymer topcoat layer, with support on a neutral bottom layer. We also show that the hybrid line-dot nanostructures have a red-shifted plasmonic response in comparison to neat gold nanowires. These template-free aligned BCPs and nanowires have potential use in nanopatterning applications, and the line-dot nanostructures should be useful in the sensing of biomolecules and other molecular species based on the plasmonic response of the nanowires.