4797wileyonlinelibrary.com photoluminescence quantum yields (PLQY). Organometal halide perovskite quantum dots (OHP-QDs) have recently emerged as bright emitters with narrow-band colors and high PLQY (up to ≈90%). [11][12][13][14] Furthermore, tuning the size or halide compositions of OHP-QDs has enabled fi ne adjustment of their emitting colors across the entire visible spectrum. [ 12,13 ] These attractive characteristics highlight the enormous potential of OHP-QDs as light-emitting materials in electroluminescence (EL) devices.However, OHP-QDs-based LEDs (OQ-LEDs) have been rarely reported, primarily due to the diffi culties in the fabrication of dense fi lms of OHP-QDs for effi cient emitting layers. OHP-QDs are usually prepared by solvent exchange or hot injection methods, but the concentration of the resultant OHP-QDs suspension is low (≈0.5 mg mL −1 ). [ 12,13 ] The subsequent enrichment of the OHP-QDs suspension is diffi cult due to easy aggregation and/or potential damage of OHP-QDs during the concentration process via evaporation. [ 15 ] As a result, it is hard to form a continuous fi lm of OHP-QDs from dilute suspensions using a common spin-coating or printing method. The lack of effi cient fabrications of dense and uniform fi lms of OHP-QDs has greatly hampered their use in high-performance EL devices.In this work, we report one-step fabrication of high-quality uniform fi lms of OHP-QDs by using a simple dip-coating method. By varying the halide composition (X = Br, Cl, and I) or tuning the size of OHP-QDs, we can readily produce uniform fi lms of OHP-QDs emitting with tunable colors from blue to green and red. Based on the OHP-QDs fi lms, we fabricated multicolor higheffi ciency OQ-LEDs with sharp emissions (FWHM smaller than 30 nm). The packaged OQ-LEDs showed robust stability in air of ≈50% humidity for at least 7 d. The remarkable performance characteristics of OQ-LEDs demonstrate the high potential of OHP-QDs as effi cient and color-tunable light emitters for lowcost display, lighting, and optical communication applications.Organometal halide perovskites quantum dots (OHP-QDs) with bright, colortunable, and narrow-band photoluminescence have signifi cant advantages in display, lighting, and laser applications. Due to sparse concentrations and diffi culties in the enrichment of OHP-QDs, production of large-area uniform fi lms of OHP-QDs is a challenging task, which largely impedes their use in electroluminescence devices. Here, a simple dip-coating method has been reported to effectively fabricate large-area uniform fi lms of OHP-QDs. Using this technique, multicolor OHP-QDs light-emitting diodes (OQ-LEDs) emitting in blue, blue-green, green, orange, and red color have been successfully produced by simply tuning the halide composition or size of QDs. The blue, green, and red OQ-LEDs exhibited, respectively, a maximum luminance of 2673, 2398, and 986 cd m −2 at a current effi ciency of 4.01, 3.72, and 1.52 cd A −1 , and an external quantum effi ciency of 1.38%, 1.06%, and 0.53%, which are much bette...

Owing to the extraordinary properties, organic micro/nanocrystals are important building blocks for future low-cost and high-performance organic electronic devices. However, integrated device application of the organic micro/nanocrystals is hampered by the difficulty in high-throughput, high-precision patterning of the micro/nanocrystals. In this study, the authors demonstrate, for the first time, a facile capillary-assisted alternating-electric field method for the large-scale assembling and patterning of both 0D and 1D organic crystals. These crystals can be precisely patterned at the photolithography defined holes/channels at the substrate with the yield up to 95% in 1 mm . The mechanism of assembly kinetics is systematically studied by the electric field distribution simulation and experimental investigations. By using the strategy, various organic micro/nanocrystal patterns are obtained by simply altering the geometries of the photoresist patterns on substrates. Moreover, ultraviolet photodetectors based on the patterned Alq3 micro/nanocrystals exhibit visible-blind photoresponse with high sensitivity as well as excellent stability and reproducibility. This work paves the way toward high-integration, high-performance organic electronic, and optoelectronic devices from the organic micro/nanocrystals.