Dramatic changes in the physical properties of composites occur when filler particles form a percolating network through the composite, particularly when the difference between the properties of the constitutive phases is large. By use of electric conductivity and dielectric properties as examples, recent studies on the physical properties of composites near percolation are reviewed. The effects of geometric factors and intrinsic properties of the fillers and the matrix, and especially of the interface between fillers and matrix, on electric and dielectric properties near percolation are discussed. Contact resistivity at the interface is less desirable for enhancing electrical conductivity. By contrast, an interface with high resistivity suppresses tunneling between adjacent fillers and leads to percolative composites with higher dielectric constant but lower dielectric loss. This review concludes with an outlook on the future possibilities and scientific challenges in the field.

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2D/3D perovskite heterostructures or composites are recognized as efficient strategies to improve the stability of perovskite solar cells. Herein, a novel solution process to develop 2D/3D perovskites with modulated diffusion passivation by introducing phenylethylammonium iodide (PEAI) and N,N‐dimethylformamide (DMF) additive, which could effectively enhance device performance and long‐term stability, is demonstrated. Compared with conventional devices, the device with PEAI and DMF solvent additive treatment exhibit enhanced charge transport, improved charge extraction, and suppressed nonradiative carrier recombination. The solar cells with an optimal 2D/3D perovskite passivation treatment exhibit an extremely high fill factor of 83.6% and an average power conversion efficiency of 21.4% (21.3% using integrated photocurrent from the incident photon‐to‐current efficiency spectra) based on the NiOx hole transport layer. Furthermore, the unencapsulated device exhibits excellent stability under continuously simulated sunlight illumination and outstanding air stability after 1000 h of storage under ambient air conditions.

To develop new composites with sufficiently high thermal conductivity and suitably controlled D k value for PCBs application, the composites were prepared from epoxy and AlN or BN fillers, and the effects of content, size, size distribution, and morphology of two fillers on the thermal and dielectric properties of the composites were investigated. The results showed that either AlN or BN fillers can greatly increase T g and thermal conductivity, decreasing CTE and D f , and suitably controlling the increase of D k . At the same filler content, BN-filled composites exhibit better thermal performance and dielectric properties compared to AlN-filled composites. In the case of BN-filled composites, it is found that plateletshaped micro-BN filled composite has lower T g and higher CTE compared with particle-shaped nano-BN filled composite, but its thermal conductivity is remarkably higher than that of nano-BN filled composite. When hybrid BN fillers are used, thermal conductivity further increases. For micro-or nano-BN filled composite, the composite shows decreased T g and increased D k at high fraction of BN, but hybrid BN-filled composite still has high T g and similar D k with epoxy even if at high fraction of BN. Compared with single-sized AlN-filled composite, it is found that hybrid-sized AlN-filled composite has higher T g and lower CTE, but has lower thermal conductivity. To predict thermal conductivity and D k in the investigated materials system, different models reported in the literature were analyzed and compared with the experimental data. Finally, suitable models were recommended.

Conventional buildings consume about 40% of global energy, smart window technologies have been developed for sunlight modulation and energy management. Most current smart windows change from transparent to opaque as the temperature rises, which is detrimental to indoor lighting at daytime or privacy protection at night. In this work, a versatile thermochromic hydrogel system by introducing sodium dodecyl sulfate (SDS) micelles into a crosslinked copolymer of hydrophilic acrylamide and hydrophobic stearyl methacrylate (C18) is developed. The liquid precursor solution can be encapsulated within two glass panels and in situ gelated to prepared smart windows, which showed excellent solar modulation ability (Tlum = 99.05%, DTsolar = 33.42%), dual responsiveness (thermal and pH) and tunable phase transition temperature (20–50 °C). Moreover, this design selectively blocks infrared light, while allowing ultraviolet and visible light through at daytime, which is beneficial for indoor illumination and heat insulation. When temperature drops at night, C18 units aggregate within SDS micelles to increase their dimensions, causing enhanced light blocking properties (opaque) to protect the customers’ privacy. The as‐prepared hydrogel‐based smart windows present a facile strategy to meet the stringent requirements of high transparency, excellent solar modulation ability, easy to fabricate and mechanical flexibility, holding great promise for the next‐generation energy‐saving buildings.

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Separated boron and nitrogen porous graphitic carbon (BNGC) is fabricated by a facile hydrothermal coordination/ZnCl2-activation process from renewable and inexpensive nitrogen-containing chitosan. In this synthetic pathway, chitosan, which has a high nitrogen content, first coordinates with Fe(3+) ions to form chitosan-Fe that subsequently reacts with boric acid (boron source) to generate the BNGC precursor. After simultaneous carbonization and ZnCl2 activation followed by removal of the Fe catalyst, BNGC, containing isolated boron and nitrogen centers and having a high surface area of 1567 m(2)  g(-1) and good conductivity, can be obtained. Results indicate that use of chitosan as a nitrogen-containing carbon source effectively prevents nitrogen atoms from direct combination with boron atoms. In addition, the incorporation of Fe(3+) ions not only endows BNGC with high graphitization, but also favors for nitrogen fixation. Remarkably, the unique microstructure of BNGC enables its use as an advanced electrode material for energy storage. As electrode material for supercapacitors, BNGC shows a high capacitance of 313 F g(-1) at 1 A g(-1), and also long-term durability and coulombic efficiency of >99.5 % after 5000 cycles. Notably, in organic electrolytes, the energy density could be up to 50.1 Wh kg(-1) at a power density of 10.5 kW kg(-1). The strategy developed herein opens a new avenue to prepare BNGC without inactive BN bonds from commercially available chitosan for high-performance supercapacitors.

All-inorganic perovskites have been intensively investigated as potential optoelectronic materials because of their excellent thermal stability, especially for CsPbI 2 Br. Herein, the authors studied the effects of mixed passivation utilizing organic phenylethylammonium bromide and inorganic ionic cesium bromide (PEABr + CsBr) on the all-inorganic perovskite (CsPbI 2 Br) solar cells for the first time. The treatment with different passivation mechanisms enhances the perovskite film quality, resulting in uniform surface morphology and compact film with low trap density. Besides, the passivation improves the energy level alignment, which benefits the hole extraction at the perovskite/HTL interface and drives the interface electron separation, suppressing the charge recombination and realizing a high open-circuit voltage (V oc ). Finally, the device represents a high power conversion efficiency (PCE) of 16.70%, a V oc of 1.30 V, and an excellent fill factor (FF) of 0.82. The V oc loss and high FF should be among the best values for CsPbI 2 Br based devices. Furthermore, the treated devices exhibit remarkable long-term stability with only 8% PCE loss after storing in a glove box for more than 1000 h without encapsulation.