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With the growing challenges of modern electronics in heat dissipation, developing thermal management materials with high thermal conductivity and electrical insulation property remains an important issue for electronics. In this work, a novel three-dimensional network (3D) of boron nitride/reduced graphene oxide (BN/rGO) with covalent bond connections were fabricated by using the surface modification and ice-templated methods. The as-prepared boron nitride/reduced graphene oxide/nature rubber composites (BN/rGO/NR) possessed an enhanced through-plane thermal conductivity of 1.28 W m−1 K−1 and satisfactory electrical insulation at a low filler loading of 4.9 vol%. The results demonstrated that the covalent bond connections and three-dimensional networks of fillers greatly reduced the interfacial thermal resistance as well as phonon scatterings at the filler/filler and filler/matrix interface simultaneously. More importantly, this strategy provided a creative insight to the design of advanced thermal management materials and also presented a bright application prospect for next-generation electronic packing. BN and rGO were connected by the covalent bonds through using the surface modified method. BN/rGO/NR composites were fabricated by the ice-templated and vacuum-assisted method. Image 1 [ABSTRACT FROM AUTHOR]

• Luminescent composites with high-thermal-conductivity is achieved via 3D-hBN network. • The mechanism of thermal conduction enhancement is explained by numerical simulation. • Optical performance of the proposed luminescent composites is tested. • Laser-excited white lighting with excellent cooling performance is demonstrated. Laser-excited white lighting, which is achieved by laser diodes and phosphor converters, has garnered increasing interest in recent years due to their high-power and high-brightness characteristics. Nevertheless, two long-standing thermal issues remain formidable: first, the photoluminescent phosphors also generate heat due to the Stokes loss, which are the second heat source in the packaging but long ignored; second, the phosphors are embedded in low-thermal-conductivity silicone and the generated heat is rather inefficient to dissipate. As a result, the accumulated heat leads to high temperature in phosphor particles and even thermal quenching, which deteriorate the luminescence, chromaticity, and reliability. In this work, these problems are successfully addressed by establishing three-dimensional (3D) boron nitride (BN) networks to cool the silicone-embedded phosphor particles in a facile and scalable method. When lighted under the driven current of 900 mA, the working temperature of phosphor layer is dramatically decreased by 95.2 °C with the 3D-BN network without sacrificing the luminescence and chromaticity. Such strategy with excellent cooling performance, high reliability, and easy scalability may hold great promise for broader optoelectronics applications beyond laser-excited white lighting. [ABSTRACT FROM AUTHOR]

• An air-bubbles-assembly strategy was proposed for constructing 3D network. • In-situ heat dissipation pathways were established inside the WLEDs. • The 3D/hBN network reduced the working temperature of QDs by 57.3°C. • FEM analysis was performed to visualize the effectiveness of the 3D network. The non-radiative electron transitions of Quantum dots (QDs) in White light-emitting diodes (WLEDs) not only generates thermal phonons with temperature rise but also degrades their photonic properties. These nanoscale heat sources are usually embedded in low-thermal-conductivity polymer matrix, which is difficult for building efficient heat dissipation pathways without sacrificing the optical performance simultaneously. Herein, we reported an air-bubbles-assembly strategy to construct three-dimensional (3D) thermal dissipation network inside the QDs-WLEDs. Owing to the lateral expulsion of massive microscale air-bubbles, an interconnected hexagonal boron nitride (hBN) network was established under an extremely low hBN loading of 2.74 wt%. With this efficient 3D/hBN network, the highest working temperature of QDs was dramatically decreased by 57.3°C at 700 mA. More than that, the 3D/hBN-WLEDs also show high luminous efficacy of 84.6 lm/W as well as superior color rendering index of Ra = 94.1 and R9 = 93.8, which are comparable to those of traditional WLEDs. The proposed strategy is expected to pave a new door for targeting cooling QDs and other photoluminescent nanoparticles at high-power applications. [ABSTRACT FROM AUTHOR]

Easy and high efficient methods are in great demand to obtain polyimide (PI) composites with high thermal conductivity in the electronic packaging field. In this work, PI/boron nitride (BN) composites with high thermal conductivity are easily fabricated. Tightly connected and well‐arranged BN platelets construct effective 3D thermally conductive networks in the PI matrix upon hot pressing, after BN platelets are coated on the surface of PI granules by the help of a kind of PI adhesive. The thermal conductivity of the PI/BN composites reaches as high as 4.47 W mK–1 at a low BN loading of 20 vol%, showing an enhancement of 2099%, compared to pure PI. Such enhancement of the thermal conductivity is the highest compared with the results in the open literature. Our work is a good example that utilized the sufficient physical connection (aggregates) of thermally conductive fillers to significantly promote the thermal conductivity of polymer composites. [ABSTRACT FROM AUTHOR]