Photoluminescence enhancement of perovskite CsPbBr3 quantum dots by plasmonic Au nanorods

Enhancing photoluminescence performance of perovskite quantum dots with plasmonic nanoparticles: insights into mechanisms and light-emitting applications

Perovskite quantum dots (QDs) are considered as promising materials for numerous optoelectronic applications due to their narrow emission spectra, high color purity, high photoluminescence quantum yields (PLQYs), and cost-effectiveness. Herein, we synthesized various types of perovskite QDs and incorporated Au nanoparticles (NPs) to systematically investigate the impact of plasmonic effects on the photoluminescence performance of perovskite QDs. The PLQYs of the QDs are enhanced effectively upon the inclusion of Au NPs in the solutions, with an impressive PLQY approaching 99% achieved. The PL measurements reveal that the primary mechanism behind the PL improvement is the accelerated rate of radiative recombination. Furthermore, we integrate perovskite QDs and Au NPs, which function as color conversion layers, with blue light-emitting diodes (LEDs), achieving a remarkable efficiency of 140.6 lm W-1. Additionally, we prepare photopatternable thin films of perovskite QDs using photocrosslinkable polymers as the matrix. Microscale patterning of the thin films is accomplished, indicating that the addition of plasmonic NPs does not adversely affect their photopatternable properties. Overall, our research not only elucidates the underlying mechanisms of plasmonic effects on perovskite QDs but presents a practical method for enhancing their optical performance, paving the way for next-generation optoelectronic applications, including high-definition micro-LED panels.

Light management for perovskite light-emitting diodes

Perovskite light-emitting diodes (LEDs) have reached external quantum efficiencies of over 20% for various colours, showing great potential for display and lighting applications. Despite the internal quantum efficiencies of the best-performing devices already approaching unity, around 80% of the internally generated photons are trapped in the devices and lose energy through a variety of lossy channels. Significant opportunities for improving efficiency and maximizing photon extraction lie in the effective management of light. In this Review we analyse light management strategies based on the intrinsic optical properties of the perovskite materials and the extrinsic properties related to device structures. These approaches should allow the external quantum efficiencies of perovskite LEDs to substantially exceed the conventional limits of planar organic LED devices. By revisiting lessons learned from organic LEDs and perovskite solar cells, we highlight possible directions of future research towards perovskite LEDs with ultrahigh efficiencies.

Highly efficient CsPbBr3@glass@polyurethane composite film as flexible liquid crystal display backlight

Inorganic lead halide perovskite quantum dots (CsPbX3 QDs (X = Cl, Br, or I)) have attracted more and more attention due to their high absorption coefficient, narrow emission band, high quantum efficiency, and tunable emission wavelength. However, CsPbX3 QDs are decomposed when exposed to bright light, heat, moisture, etc., which leads to severe luminous attenuation and limits their commercial application. In this paper, CsPbBr3@glass materials were successfully synthesized by a one-step self-crystallization method, including melting, quenching and heat treatment processes. The stability of CsPbBr3 QDs was improved by embedding CsPbBr3 QDs into zinc-borosilicate glass. Then, the CsPbBr3@glass was combined with polyurethane (PU) to form a flexible composite luminescent film CsPbBr3@glass@PU. This strategy enables the transformation of rigid perovskite quantum dot glass into flexible luminescent film materials and further improves the photoluminescence quantum yield (PLQY) from 50.5% to 70.2%. The flexible film has good tensile properties, and its length can be strained 5 times as long as the original length. Finally, a white LED was encapsulated by combining CsPbBr3@glass@PU film and red phosphor K2SiF6:Mn4+ with a blue LED chip. The good performance of the obtained CsPbBr3@glass@PU film indicates that it has potential application in flexible liquid crystal displays (LCDs) as a backlight source.

Manipulation of the photoluminescence of lead halide perovskite quantum dots with mechanically reconfigurable 3D photonic crystals

Reconfigurable 3D photonic crystals (3DPCs) are promising for dynamic emission devices, owing to their unique properties. Here, we integrated the perovskite quantum dot film together with 3D reconfigurable photonic crystals (PCs) to form quantum dot/photonic crystal heterostructures and investigated their interactions at their interfaces. The photonic bandgaps of the presented 3DPCs can be dynamically tuned by heating and applying external mechanical forces, and they can be stably fixed in the intermediate states. By tuning the photonic bandgaps of the 3DPCs, a maximum photoluminescence (PL) enhancement of 11 times that of CsPb(I/Br)₃ quantum dots has been achieved. It has been revealed that the combined effects of increased density of photon states and the greatly confined and enhanced electric field on the upper surface of 3DPCs contribute to the enhanced Purcell effect, which in turn leads to the enhanced photoluminescence.

Plasmonic-perovskite solar cells, light emitters, and sensors

The field of plasmonics explores the interaction between light and metallic micro/nanostructures and films. The collective oscillation of free electrons on metallic surfaces enables subwavelength optical confinement and enhanced light-matter interactions. In optoelectronics, perovskite materials are particularly attractive due to their excellent absorption, emission, and carrier transport properties, which lead to the improved performance of solar cells, light-emitting diodes (LEDs), lasers, photodetectors, and sensors. When perovskite materials are coupled with plasmonic structures, the device performance significantly improves owing to strong near-field and far-field optical enhancements, as well as the plasmoelectric effect. Here, we review recent theoretical and experimental works on plasmonic perovskite solar cells, light emitters, and sensors. The underlying physical mechanisms, design routes, device performances, and optimization strategies are summarized. This review also lays out challenges and future directions for the plasmonic perovskite research field toward next-generation optoelectronic technologies.

Enhanced photoluminescence of CsPbBr3-xIx nanocrystals via plasmonic Au nanoarrays

Large scale ordered Au nanoarrays are fabricated by nanosphere lithography technique. The photoluminescence improvement of CsPbBr_3-xI_x nanocrystals by more than three times is realized in the CsPbBr_3-xI_x nanocrystal/Au nanoarray/Si structure. Time-resolved photoluminescence decay curves indicate that the lifetime is decreased by introducing the Au nanoarrays, which results in a increasing radiation recombination rate. The reflection spectra with two major valleys (the dip in the curve) located at ∼325 nm and 545 nm of Au nanoarray/Si structure, which illustrates two plasmonic resonance absorption peaks of the Au nanoarrays. The enhancement of photoluminescence is ascribed to a well match between the excitation/emission of CsPbBr_3-xI_x nanocrystals and localized surface plasmon/gap plasmon resonance absorption of the ordered Au nanoarrays, as also revealed from the finite-difference time-domain simulation analysis. Our work offers an effective strategy to improve the fluorescence of perovskite nanocrystals and provide the potential for further applications.

Surface-Plasmon-Enhanced Perovskite Light-Emitting Diodes

Perovskite light-emitting diodes (PeLEDs) have attracted considerable attention because of their potential in display and lighting applications. To promote commercialization of PeLEDs, it is important to improve the external quantum efficiency of the devices, which depends on their internal quantum efficiency (IQE) and light extraction efficiency. Optical simulations have revealed that 20-50% of the light generated in the device will be lost to surface plasmon (SP) modes formed in the metal/dielectric interfaces. Therefore, extracting the optical energy in SP modes to the air will greatly increase the light extraction efficiency of PeLEDs. In addition, the SPs can accelerate radiative recombination of the emitter via near-field effects. Thus, the IQE of a PeLED can also be enhanced by SP manipulation. In this review, first, general concepts of the SPs and how they can enhance the efficiency of LEDs are introduced. Then recent progresses in SP-enhanced emission of perovskite films and LEDs are systematically reviewed. After that, the challenges and opportunities of the SP-enhanced PeLEDs are shown, followed by an outlook of further development of the SPs in perovskite optoelectronic devices.