Binary Host-induced Exciplex Enabled High Color-Rendering Index of 94 for Carbon Quantum Dot-Based White Light-Emitting Diodes.

White light-emitting diodes (WLEDs) with high color-rendering index (CRI, >90) are important for backlight displays and solid-state lighting applications. Although the well-developed colloidal quantum dots (QDs) based on heavy metals such as cadmium and lead are promising candidates for WLEDs, the low CRI still remains a significant limitation. In addition, the severe toxicity of heavy metals greatly limits their widespread use. Herein, the study demonstrates low-cost and environmentally friendly carbon quantum dots (CQDs)-based WLEDs that exhibit a high CRI of 94.33, surpassing that of conventional cadmium/lead-containing QD-based WLEDs. This achievement is attained through the employment of a binary host-induced exciplex strategy. The high hole/electron mobility and suitable energy levels of the donor and acceptor give rise to a broadband orange-yellow emission stemming from the exciplex. As the host, the binary exciplex is capable of contributing blue and orange-yellow emission components while efficiently mitigating the aggregation-induced quenching of CQDs. Meanwhile, CQDs effectively address the deep-red emission gap, enabling the realization of CQDs-based WLEDs with high CRI. These WLEDs also exhibit a remarkably low turn-on voltage of 2.8 V, a maximum luminance exceeding 2000 cd m- 2, a correlated color temperature of 4976 K, and Commission Internationale de l'Eclairage coordinates of (0.34, 0.32).

Dynamic range enhancement of self-referenced spectral interferometry with extended time excursion method by the cascaded Kerr lens process.

Self-referenced spectral interferometry with extended time excursion (SRSI-ETE) is a powerful method for single-shot characterization of the temporal contrast of a high peak power laser, which has high temporal resolution but a low dynamic range. Here, a temporal contrast reduction method is proposed that uses the cascaded Kerr lens process in two thin glass plates. Combined with the SRSI-ETE method, the measurement dynamic range of the method is increased about two orders of magnitude while having a 20 fs temporal resolution and a 40 ps time window in single shot.

Ultra-Narrow-Bandwidth Deep-Red Electroluminescence Based on Green Plant-Derived Carbon Dots.

Deep-red light-emitting diodes (DR-LEDs, >660 nm) with high color-purity and narrow-bandwidth emission are promising for full-color displays and solid-state lighting applications. Currently, the DR-LEDs are mainly based on conventional emitters such as organic materials and heavy-metal based quantum dots (QDs) and perovskites. However, the organic materials always suffer from the complicated synthesis, inferior color purity with full-width at half-maximum (FWHM) more than 40 nm, and the QDs and perovskites still suffer from serious problems related to toxicity. Herein, this work reports the synthesis of efficient and high color-purity deep-red carbon dots (CDs) with a record narrow FWHM of 21 nm and a high quantum yield of more than 50% from readily available green plants. Moreover, an exciplex host is further established using a polymer and small molecular blend, which has been shown to be an efficient strategy for producing high color-purity monochrome emission from deep-red CDs via Förster energy transfer (FET). The deep-red CD-LEDs display high color-purity with Commission Internationale de l'Eclairage (CIE) coordinates of (0.692, 0.307). To the best of the knowledge, this is the first report of high color-purity CD-LEDs in the deep-red region, opening the door for the application of CDs in the development of high-resolution light-emitting display technologies.