Transient Optical Properties of CsPbX₃/Poly(maleic anhydride‐alt‐1‐octadecene) Perovskite Quantum Dots for White Light‐Emitting Diodes

Abstract

Poly(maleic anhydride‐alt‐1‐octadecene) (PMAO)‐coated green CsPbBr3 and red CsPbBr0.6I2.4 quantum dots (QDs), as the phosphor materials for white light‐emitting diodes (WLEDs), are reported. The anhydride groups of PMAO can be bound to the surface ligands of perovskite QDs and act as a protective layer. The results show that CsPbX3/PMAO (X = Cl, Br, I) presents good crystallinity and excellent luminescence properties. Time‐resolved photoluminescence (TRPL) shows that the PL lifetime of CsPbX3/PMAO is prolonged, and the transient absorption (TA) results show that intraband hot‐exciton relaxation and exciton recombination can be slowed down when the CsPbX3 QDs are coated with PMAO. However, the PL quantum yields (PLQYs) increase for both the green‐emitting QDs and the red‐emitting QDs after PMAO coating. WLED devices are fabricated by integrating the green CsPbBr3/PMAO QDs and red CsPbBr0.6I2.4/PMAO QDs on the blue GaN chips. The devices show stable white light emission with Commission Internationale de L'Eclairage (CIE) color coordinates of (0.314, 0.291). The results indicate that CsPbX3/PMAO QDs can be an ideal downconversion fluorescent material for WLED devices.

Ultrasmall CsPbBr3 Quantum Dots with Bright and Wide Blue Emissions

“…The photophysical properties of inorganic lead halide perovskite CsPbX 3 (X ¼ CI, Br, I) nanocrystals (NCs), including high photoluminescence quantum yield (PLQY) and large absorption cross-section, [1,2] render these materials extremely attractive for a range of potential applications, such as light-emitting diodes, [3] lasers, [4,5] and solar cells. [6,7] The structural flexibility of these materials results in various types extending from nanoplates (NPLs, 2D) [8] to nanowires (NWs, 1D), and even quantum dots (QDs, 0D).…”

Strategies of Improving CsPbX3 Perovskite Quantum Dots Optical Performance

“…Meyns et al (2016) introduced poly (PMA) to coat perovskite QDs and improve its stability, where the diamine polymerization can further enhance the combination of OA and OAm ligands with the perovskite QD surfaces, thereby effectively improving the QD stability. Xu et al (2020b) used poly maleic anhydride-alt-1-octadicene (PMAO) to coat the CsPbX 3 QDs. The PMAO could act as a protective layer by combining its anhydride group with the surface ligands of the perovskite QDs.…”

Encapsulation of perovskite quantum dots into a LnIII-incorporating polymer matrix to achieve white light emission

“…However, the rapid anion exchange between PQDs with different compositions has been a challenge for the realization of high-performance white light emission (WLE). [21][22][23] Three main strategies, namely ion doping, [24][25][26] surface passivation 27,28 and encapsulation engineering, [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] have been developed to improve the stabilities of PQDs. Among them, encapsulation engineering can effectively prevent water and oxygen in the environment from entering PQDs, which is the most effective strategy in practice.…”

“…So far, a variety of matrixes have been explored to encapsulate PQDs, including porous zeolites, 29 amorphous alumina, 30 mesoporous silica, 31 solid paraffins, 32 inorganic amorphous glasses [33][34][35] and polymer matrixes, [36][37][38][39][40][41][42][43] among which certain matrixes have been investigated for the realization of stable WLE involving mixed PQDs and for the improvement of the environmental stabilities of PQDs. Lin 33 et al used in situ precipitation to encapsulate CsPbX 3 (X = Br, Br/I) into inorganic glass to greatly improve the stability of QDs to water and heat.…”

“…Zeng 36 et al investigated polymethyl methacrylate as the matrix to encapsulate red and green light-emitting PQDs, combined with GaN blue light chips for the preparation of white light-emitting devices (WLEDs); Sun 44 et al chose (3-aminopropyl) triethoxysilane (APTES) as both the capping agent for inorganic perovskite QDs and the precursor for a silica matrix and synthesized PQD/SiO 2 composites through a one-pot reaction, which was also combined with blue light chips to realize WLE. Xu 42 et al incorporated poly(maleic anhydride- alt -1-octadecene) (PMAO) into the synthesis of PQDs, leading to significantly increased PLQY and optical stability of the PQDs; monochromatic green and white LEDs with narrow bandwidths and appealing color characteristics were also realized. Wu 32 et al prepared paraffin/PQD composites by encapsulating blue–green–red PQDs using solid paraffins to obtain white phosphors and achieved WLE from multicomponent PQDs without incorporating blue chips.…”