Carrier spins in semiconductor nanocrystals are promising candidates for quantum information processing. Using a combination of time-resolved Faraday rotation and photoluminescence spectroscopies, we demonstrate optical spin polarization and coherent spin precession in colloidal CsPbBr 3 nanocrystals that persists up to room temperature. By suppressing the influence of inhomogeneous hyperfine fields with a small applied magnetic field, we demonstrate inhomogeneous hole transverse spin-dephasing times (! ! *) that approach the nanocrystal photoluminescence lifetime, such that nearly all emitted photons derive from coherent hole spins. Thermally activated LO phonons drive additional spin dephasing at elevated temperatures, but coherent spin precession is still observed at room temperature. These data reveal several major distinctions between spins in nanocrystalline and bulk CsPbBr 3 and open the door for using metal-halide perovskite nanocrystals in spin-based quantum technologies.

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In 2018, several major breakthroughs have been achieved in organic solar cells (OSCs) with the record power conversion efficiency (PCE) reaching over 17 %. With this increased efficiency, it is time to take a step forward to consider how to convert this technology into large scale production. For this, the economic and environmental profile of OSCs should be taken seriously‐simplified synthetic routes and green chemistry methods should be applied. According to previous studies, OSCs are competitive and profitable in the commercial market. However, toxic and/or hazardous chemicals are currently used in materials synthesis and device fabrication of OSCs. In this account, we will talk about contributions and efforts we have made to minimize the economic and environmental disadvantages in the production of OSCs. We will start with the background on how our projects were conceived and will specifically discuss our work on direct arylation and green solvent. Developments of direct arylation for synthesizing conjugated polymers will be illustrated along with our recent finding regarding the effect of green solvents on device performance and stability.

Green chemistry and a natural product together provide a cost-effective, safe and scalable solution to create luminophores with suppressed aggregation quenching in organic semiconductors.

Inorganic lead halide perovskite nanocrystals (NCs) are an exciting class of luminescent materials with high defect tolerance and broad spectral tunability, but such NCs are vulnerable to degradation under ambient conditions. Here, we report a class of modular zwitterion-functionalized isopropyl methacrylate polymers designed to stabilize a wide variety of perovskite NCs of different compositions, while also enabling processing in green solvents. Specifically, we report polymers in which the zwitterion spacing is tuned to accommodate the different lattice parameters of CsPb(Cl 1−x Br x ) 3 and CsPbI 3 NCs, and we report partially fluorinated polymers prepared to accommodate the needs of infrared-emitting NCs. We show that as-synthesized CsPbBr 3 , CsPbI 3 , and Yb 3+ :CsPbCl 3 NCs are easily transferred into these zwitterionic polymers via a simple ligand-exchange procedure. These NC/polymer composites were then cast into thin films that showed substantially improved photoluminescence (PL) and stability compared with more conventional NC/polymer films. Specifically, CsPbBr 3 and CsPbI 3 NCs in films of their appropriately designed polymers had PL quantum yields of ∼90% and ∼80%, respectively. PL quantum yields decreased under continuous illumination but self-healed completely after dark storage. We also found that all the NC compositions studied here maintain their PL quantum yields in NC/polymer composite films even after 1 year of ambient storage. These encouraging results demonstrate the utility of such modular zwitterion-functionalized polymers for hosting specific perovskite NCs, potentially opening avenues for robust new photonic applications of this important class of NCs.

Second-order NLO effects can be separated into two broad categories. The first category involves how light waves interact with an NLO medium, and it includes second-harmonic generation, sum-frequency generation, difference-frequency generation, and optical rectification. In the second category, called the electro-optic effect, an applied external electric field induces a linear change in refractive index of the NLO material. [10] Applications of the EO effect include phase modulators, Mach-Zehnder interferometers (Figure 1), in-phase-quadrature modulators, resonant antennae modulators, and ring resonators (wavelength division multiplexers), which are incredibly important commercially for transducing electrical to optical signals at high frequencies (GHz) for telecommunications over photonics fiber/wireless networks. The dominant EO material used commercially is lithium niobate, which is an inorganic crystal; however, organic materials have an inherent advantage for high-frequency applications as the polarization response in an organic molecule is dependent on the motions of electrons, which yield response times much faster (10 −14 s) than the polarization response times of inorganic EO materials (10 −10 s) which depend on the motions of ions. [10] Over the past ≈20 years, UW researchers (in the groups of Profs.

Inorganic–organic interfaces: a tutorial on using organic functional groups to enhance the performances and/or enable new functionality of inorganic nanomaterials.

Organic hybrid light-emitting diodes (hybrid-LEDs) employ organic dyes as light converters on top of commercial blue inorganic LEDs, replacing incumbent inorganic phosphor light converters synthesized from rare-earth and/or toxic metallic...