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Kang, Zhitao

Publications and source records attributed to Kang, Zhitao.

Unconventional route to dual-shelled organolead halide perovskite nanocrystals with controlled dimensions, surface chemistry, and stabilities

The past few years have witnessed rapid advances in the synthesis of high-quality perovskite nanocrystals (PNCs). However, despite the impressive developments, the stability of PNCs remains a substantial challenge. The ability to reliably improve stability of PNCs while retaining their individual nanometer size represents a critical step that underpins future advances in optoelectronic applications. Here, we report an unconventional strategy for crafting dual-shelled PNCs (i.e., polymer-ligated perovskite/SiO 2 core/shell NCs) with exquisite control over dimensions, surface chemistry, and stabilities. In stark contrast to conventional methods, our strategy relies on capitalizing on judiciously designed star-like copolymers as nanoreactors to render the growth of core/shell NCs with controlled yet tunable perovskite core diameter, SiO 2 shell thickness, and surface chemistry. Consequently, the resulting polymer-tethered perovskite/SiO 2 core/shell NCs display concurrently a stellar set of substantially improved stabilities (i.e., colloidal stability, chemical composition stability, photostability, water stability), while having appealing solution processability, which are unattainable by conventional methods.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Hybrid Down-Converting Structures for Solid State Lighting

Achieving higher luminous efficacy in phosphor converted light emitting diodes (pcLED) requires breakthroughs in down-converting materials that provide high conversion efficiency, tunable narrow bandwidth emission, and temperature/chemical stability. While conventional bulk phosphors are currently the dominant down-converters used in high power solid-state lighting (SSL) applications, their performance is limited by intrinsic properties such as high scattering cross-sections and large emission bandwidth. On the other hand, conventional luminescent nanocrystals (e.g, quantum dots or QDs) have high self-absorption and poor thermal and chemical stability for HB LEDs. Ultimately, these materials will enable a new generation of solid state lighting devices with high luminous efficacies, high color and thermal stability, and with spectral efficiency near the theoretical maximum luminous efficacy of radiation (LER), as a result of their color tunability and narrow bandwidths (FWHM < 30nm).

36 MATERIALS SCIENCE↗