Compared with polycrystalline films, single-crystalline methylammonium lead halide (MAPbX, X = halogen) perovskite nanowires (NWs) with well-defined structure possess superior optoelectronic properties for optoelectronic applications. However, most of the prepared perovskite NWs exhibit properties below expectations due to poor crystalline quality and rough surfaces. It also remains a challenge to achieve aligned growth of single-crystalline perovskite NWs for integrated device applications. Here, we report a facile fluid-guided antisolvent vapor-assisted crystallization (FGAVC) method for large-scale fabrication of high-quality single-crystalline MAPb(IBr) (x = 0, 0.1, 0.2, 0.3, 0.4) NW arrays. The resultant perovskite NWs showed smooth surfaces due to slow crystallization process and moisture-isolated growth environment. Significantly, photodetectors made from the NW arrays exhibited outstanding performance in respect of ultrahigh responsivity of 12 500 A W, broad linear dynamic rang (LDR) of 150 dB, and robust stability. The responsivity represents the best value ever reported for perovskite-based photodetectors. Moreover, the spectral response of the MAPb(IBr) NW arrays could be sequentially tuned by varying the content of x = 0-0.4. On the basis of this feature, the NW arrays were monolithically integrated to form a unique system for directly measuring light wavelength. Our work would open a new avenue for the fabrication of high-performance, integrated optoelectronic devices from the perovskite NW arrays.

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...

Ruddlesden-Popper perovskite, (PEA) 2 PbBr 4 (PEA = C 8 H 9 NH 3 ), is a steady and inexpensive material with a broad bandgap and a narrow-band emission. These features make it a potential candidate for deep-blue light-emitting diodes (LEDs). However, due to the weak exciton binding energy, LEDs based on the perovskite thin films usually possess a very low external quantum efficiency (EQE) of <0.03%. Here, for the first time, the construction of high-performance deep-blue LEDs based on 2D (PEA) 2 PbBr 4 nanoplates (NPs) is demonstrated. The as-fabricated (PEA) 2 PbBr 4 NPs film shows a deep-blue emission at 410 nm with excellent stability under ambient conditions. Impressively, LEDs based on the (PEA) 2 PbBr 4 NPs film deliver a bright deep-blue emission with a maximum luminance of 147.6 cd m −2 and a high EQE up to 0.31%, which represents the most efficient and brightest perovskite LEDs operating at deep-blue wavelengths. Furthermore, the LEDs retain over 80% of their efficiencies for over 1350 min under ≈60% relative humidity. The steady and bright deep-blue LEDs can be used as an excitation light source to realize white light emission, which shows the potential for light communication. The work provides scope for developing perovskite into efficient and deep-blue LEDs for low-cost light source and light communication.

Organic–inorganic hybrid perovskite (CH3NH3PbX3, X = Cl, Br, or I) quantum dots with superior optoelectronic properties, including bright, colour-tunable, narrow-band photoluminescence and high photoluminescence quantum efficiency, are regarded as ideal materials for next-generation displays.

Organic‐inorganic hybrid perovskite (CH3NH3PbX3, X = Cl, Br or I) quantum dots (QDs) have shown superior optoelectronic properties and have been regarded as a most ideal material for next‐generation optoelectronic devices, particularly for QDs‐based light‐emitting diodes (QLEDs). However, there are only a few reports on CH3NH3PbX3 QLEDs and the reported performance is still very poor, primarily due to the difficulties in the fabrication of high‐quality compact QDs thin films. In this work, an electric‐field‐assisted strategy is developed for efficient fabrication of uniform CH3NH3PbBr3 QDs thin films with high photoluminescence quantum yields (PLQY, 80%–90%) from dilute CH3NH3PbBr3 QDs suspensions (≈0.1 mg mL‐1) within 5 mins. Benefited from the high‐quality CH3NH3PbBr3 QDs thin films, the corresponding QLEDs deliver a highly bright green emission with maximum luminances of 12450 cd m2. Furthermore, a current efficiency of 12.7 cd A‐1, a power efficiency of 9.7 lm W‐1, and an external quantum efficiency (EQE) of 3.2% were acheived by enhancing the hole injection. This performance represents the best results for CH3NH3PbBr3 QDs‐based QLEDs reported to date. These results indicate an important progress in the fabrication of high‐performance CH3NH3PbX3 QLEDs and demonstrate their huge potential for next‐generation displays and lighting.