All present designs of perovskite light-emitting diodes (PeLEDs) stem from polymer light-emitting diodes (PLEDs) or perovskite solar cells. The optimal structure of PeLEDs can be predicted to differ from PLEDs due to the different fluorescence dynamics and crystallization between perovskite and polymer. Herein, a new design strategy and conception is introduced, "insulator-perovskite-insulator" (IPI) architecture tailored to PeLEDs. As examples of FAPbBr and MAPbBr , it is experimentally shown that the IPI structure effectively induces charge carriers into perovskite crystals, blocks leakage currents via pinholes in the perovskite film, and avoids exciton quenching simultaneously. Consequently, as for FAPbBr , a 30-fold enhancement in the current efficiency of IPI-structured PeLEDs compared to a control device with poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) as hole-injection layer is achieved-from 0.64 to 20.3 cd A -while the external quantum efficiency is increased from 0.174% to 5.53%. As the example of CsPbBr , compared with the control device, both current efficiency and lifetime of IPI-structured PeLEDs are improved from 1.42 and 4 h to 9.86 cd A and 96 h. This IPI architecture represents a novel strategy for the design of light-emitting didoes based on various perovskites with high efficiencies and stabilities.

Interfacial ligand passivation engineering has recently been recognized as a promising avenue, contributing simultaneously to the optoelectronic characteristics and moisture/operation tolerance of perovskite solar cells. To further achieve a win-win situation of both performance and stability, an innovative conjugated aniline modifier (3-phenyl-2-propen-1-amine; PPEA) is explored to moderately tailor organolead halide perovskites films. Here, the conjugated PPEA presents both "quasi-coplanar" rigid geometrical configuration and distinct electron delocalization characteristics. After a moderate treatment, a stronger dipole capping layer can be formed at the perovskite/ transporting interface to achieve favorable banding alignment, thus enlarging the built-in potential and promoting charge extraction. Meanwhile, a conjugated cation coordinated to the surface of the perovskite grains/units can form preferably ordered overlapping, not only passivating the surface defects but also providing a fast path for charge exchange. Benefiting from this, a ≈21% efficiency of the PPEA-modified solar cell can be obtained, accompanied by long-term stability (maintaining 90.2% of initial power conversion efficiency after 1000 h testing, 25 °C, and 40 ± 10 humidity). This innovative conjugated molecule "bridge" can also perform on a larger scale, with a performance of 18.43% at an area of 1.96 cm 2 .

Long alkyl-chain capping ligands are indispensable for preparing stable colloidal quantum dots. However, its insulating feature blocks efficient carrier transport among QDs, leading to inferior performance in light-emitting diodes (LEDs). The trade-off between conductivity and colloidal stability of QDs has now been overcome. Methylamine lead bromide (MAPbBr ) QDs with a conjugated alkyl-amine, 3-phenyl-2-propen-1-amine (PPA), as ligands were prepared. Owing to electron cloud overlapping and the delocalization effect of conjugated molecules, the conductivity and carrier mobility of PPA-QDs films increased almost 22 times over that of OA-QD films without compromising colloidal stability and photoluminescence. PPA-QDs LEDs exhibit a maximum current efficiency of 9.08 cd A , which is 8 times of that of OA-QDs LEDs (1.14 cd A ). This work provides critical solution for the poor conductivity of QDs in applications of energy-related devices.

The manipulation of nanobuilding blocks into a 3D macroscopic monolith with ordered hierarchical structures has been much desired for broad and large-scale practical applications of nanoarchitectures. In this paper, we demonstrate a fully bottom-up strategy for the preparation of aramid aerogel monoliths. The process starts from the synthesis of poly­(p-phenylene terephthalamide) (PPTA) through the polycondensation of p-phenylenediamine and terephthaloyl chloride, with the assistance of a nonreactive dispersing agent (polyethylene glycol dimethyl ether), which helps the dispersal of the as-synthesized PPTA in an aqueous medium for the formation of p-aramid nanofibers (ANF). Then the vacuum-assisted self-assembly (Vas) technique is skillfully connected with the ice-templated directional solidification (I) technique, and the combined VasI method successfully tailors the self-assembly of ANF to transform the 1D nanofibers into a 3D aerogel monolith with a specific long-range aligned, lasagna-like, multilaminated internal structure. The study of the aerogel microstructure revealed the dependence of the lamina orientation on the direction of the freezing front of ice crystals. This direction should be parallel to the deposition plane of the Vas process if a long-range aligned lamellar structure is desired. The anisotropy of the multilaminated aerogel was proven by the different results in the radial and axial directions in the compression and thermal conductivity tests. As a kind of organic aerogel, the ANF monolith has typical low density, high porosity, and low thermal conductivity. Additionally, the ANF monolith exhibits high compressive stress and excellent thermal stability. Considering its high performance and facile preparation process, potential applications of the ANF aerogel monolith can be expected.

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