Vacuum‐Drying Processed Micrometer‐Thick Stable CsPbBr₃ Perovskite Films with Efficient Blue‐To‐Green Photoconversion

Abstract

toward stability are yet needed since the lifetime of the reported devices is too short for consumer applications.Besides the application in LEDs, perovskite materials have also been adopted as downconverters in the backlight for liquid crystal displays (LCDs). [9][10][11] In 2016, Zhou et al. demonstrated stable green emissive films composed of MAPbBr 3 nanocrystals embedded polymer matrix through an in situ process. [10] Color gamut of 121% National Television Standards Committee was achieved by integrating these perovskite polymer composite films and red emissive phosphor with blue InGaN chips. In the same year, Wang et al. realized comparable results through swelling-deswelling microencapsulation strategy. [11] Both of the aforementioned films are proved to be ultrastable even in ambient atmosphere, which manifest considerate possibilities for their future commercialization. In 2018, Naijun et al. successfully applied perovskite films into an LCD prototype for the first time. [9] In backlight applications, the photonic energy conversion of short-wavelength light sources is generally incomplete, therefore, incorporation of color filters is inevitable. However, when it comes to the incorporation of suitable materials as color-conversion layers (CCLs) for visible blue light to achieve full color display, complete photoconversion should be enabled. Perovskite materials originally possess the potential to be utilized as CCLs for visible blue light due to their rather high photoluminescence quantum yields (PLQYs) and bright vivid colors. [12][13][14] Nevertheless, there is still no demonstration of perovskite materials for CCL applications. The pivotal requirement for CCLs is to realize complete energy conversion from short-wavelength light sources (such as: blue light). However, if the CCL is not thick enough, a portion of back light will remain unconverted thereby resulting in incomplete photoconversion. Currently, spin casting is the most widely adopted method to fabricate perovskite films while it is only suitable for nanometerthick films which are not adequately thick to be employed as CCLs. Therefore, a key challenge for perovskite materials to apply them as CCLs is to obtain films with higher thickness. Solvent annealing [15,16] or gas-solid [17] methods have been used to fabricate over one micrometer-thick perovskite films, however, they are still not sufficiently thick for efficient photoconversion. Metal halide perovskite materials have attracted great attention owing to their fascinating optoelectronic characteristics and low cost fabrication via facile solution processing. One of the potential applications of these materials is to employ them as color-conversion layers (CCLs) for visible blue lightto achieve full-color displays. However, obtaining thick perovskite films to realize complete color conversion is a key challenge. Here, the fabrication of micrometer-level thick CsPbBr 3 perovskite films is presented through a facile vacuum drying approach. An efficient green photoconversion is realized in a ...

Sensitivity and Detection Limit of Spectroscopic‐Grade Perovskite CsPbBr3 Crystal for Hard X‐Ray Detection

“…For practical applications in photon counting, the required X‐ray detector has to be in bulk crystal form. Even though polycrystalline films of perovskites with various thicknesses have been fabricated by solution processing, melt processing, [ 17,18 ] vacuum deposition, [ 31 ] and solution mist deposition, [ 32 ] it is challenging to produce films thicker than 1 mm and at the same time achieve the required charge transport properties. [ 9 ] In contrast, the Bridgman growth method used industrially is a feasible way to grow inch‐size CsPbBr 3 single crystals (Figure 1c).…”

Full‐Color Micro‐LED Display with CsPbBr3 Perovskite and CdSe Quantum Dots as Color Conversion Layers

“…In our recent reports, we have shown efficient photoconversion in micrometer‐thick uniform perovskite and inorganic QD films through inkjet printing (IJP) with UV‐induced polymerization or vacuum‐drying approach. [ 24–27 ] Here, by addressing the aforementioned issues, we successfully demonstrate a 4‐in. full‐color prototype based on blue micro‐LED backlight and QD CCLs.…”

Pulsed Laser Deposition of CsPbBr3 Films: Impact of the Composition of the Target and Mass Distribution in the Plasma Plume

“…Unlike the prototypical all-inorganic halide perovskite CsPbI 3 that is unstable under ambient conditions, the excellent photophysical properties of cesium lead bromide (CsPbBr 3 ) perovskite [1,11,12] have boosted the research activity towards its applications in numerous fields including photovoltaics [13][14][15][16][17], light-emitting diodes [18][19][20], photodetectors [21][22][23], lasing [24,25], field effect transistors [26] and color-conversion layers [27]. In regard to thermal stability and crystal structure, CsPbBr 3 perovskite has a yellow orthorhombic phase at room temperature and transforms to a tetragonal phase at 88 • C and to the orange cubic phase at 130 • C [28].…”

“…Additionally, the different solubility of PbBr 2 and CsBr in aprotic solvents results in the precipitation of CsBr-or PbBr 2 -rich compounds alongside the desired CsPbBr 3 phase and the low solubility of CsBr salt causes poor element distribution and poor surface coverage [43,44]. Therefore, in practice, solution-based methods yield poor reproducibility, uniformity and control on the desired composition over a large area coverage [27,45].…”