In this work, nitrogen-rich carbon nanodots (CNDs) are prepared by the emulsion-templated carbonization of polyacrylamide. The formation mechanism and chemical structure are investigated by infrared, nuclear magnetic resonance, and X-ray photoelectron spectroscopies. Transmission electron microscopy also reveals that the obtained CNDs have well-developed graphitic structure and narrow size distribution without any size selection procedure. We vary the molecular weight of the polymer to control the size of the CNDs and finally obtain the CNDs rendering bright visible light under UV illumination with a high quantum yield of 40%. Given that the CNDs are worth utilizing in phosphor applications, we fabricate large-scale (20 × 20 cm) freestanding luminescent films of the CNDs based on a poly(methyl methacrylate) matrix. The polymer matrix can not only provide mechanical support but also disperse the CNDs to prevent solid-state quenching. For practical application, we demonstrate white LEDs consisting of the films as color-converting phosphors and InGaN blue LEDs as illuminators. Such white LEDs exhibit no temporal degradation in the emission spectrum under practical operation conditions. This study would suggest a promising way to exploit the luminescence from solid-state CNDs and offer strong potential for future CND-based solid-state lighting systems.

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The interest in low processing temperature for printable transistors is rapidly increasing with the introduction of a new form factor in electronics and the growing importance of high throughput. This paper reports the fabrication of low-temperature-processable enhancement-mode amorphous oxide thin-film transistors (TFTs) using the solution process. A facile low-pressure annealing (LPA) method is proposed for the activation of indium oxide (InOx) semiconductors at a significantly low processing temperature of 200 °C. Thermal annealing at a pressure of about ~10 Torr induces effective condensation in InOx even at a low temperature. As a result, the fabricated LPA InOx TFTs not only functioned in enhancement mode but also exhibited outstanding switching characteristics with a high on/off current ratio of 4.91 × 109. Furthermore, the LPA InOx TFTs exhibit stable operation under bias stress compared to the control device due to the low concentration of hydroxyl defects.

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