Patterning Multicolor Hybrid Perovskite Films via Top-Down Lithography
TL;DR: A study on the effect of different lithographic solvents on perovskite films is performed and this insight is used to develop photolithography and electron-beam lithography procedures for patterning perovkite films, which achieves micron-scale features with flat tops.
Abstract: Lead-halide perovskites have attracted great attention due to their excellent optoelectronic properties, with rapid progress being made in their performance as light-emitting diodes (LEDs), photodiodes, and solar cells. Demonstrating large scale, high-resolution patterning of perovskites is a key enabling step to unlock their full potential for a range of optoelectronic applications. However, the development of a successful top-down lithography fabrication procedure has so far been hampered by the incompatibility of perovskite films with the solvents used during lithographic processes. Here, we perform a study on the effect of different lithographic solvents on perovskite films and use this insight to develop photolithography and electron-beam lithography procedures for patterning perovskite films. This procedure uses standard resists at low temperatures and achieves micron-scale features with flat tops. Furthermore, we expand this platform to produce arrays of multicolor pixels for potential commercial perovskite LED display applications.
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TL;DR: In this paper , a review of the development of perovskite light-emitting diodes is presented, exploring the key challenges involved in creating efficient and stable devices.
Abstract: Light-emitting diodes based on halide perovskites have undergone rapid development in recent years and can now offer external quantum efficiencies of over 23%. However, the practical application of such devices is still limited by a number of factors, including the poor efficiency of blue-emitting devices, difficulty in accessing emission wavelengths above 800 nm, a decrease in external quantum efficiency at high current density, a lack of understanding of the effect of the electric field on mobile ions present in the perovskite materials, and short device lifetimes. Here we review the development of perovskite light-emitting diodes. We examine the key challenges involved in creating efficient and stable devices, and consider methods to alleviate the poor efficiency of blue-emitting devices, leverage emission in the long infrared region and create spin-polarized light-emitting diodes. This Review examines the development of perovskite light-emitting diodes, exploring the key challenges involved in creating efficient and stable devices.
131 citations
TL;DR: This work demonstrates a high-resolution, large-scale photolithographic method to pattern multicolor perovskite films based on a dry lift-off process which involves the use of parylene as an intermediary and the easy mechanical peeling-off of pARYlene films on various substrates.
Abstract: Metal halide perovskites are emerging as attractive materials for light-emitting diode (LED) applications. The external quantum efficiency (EQE) has experienced a rapid progress and reached over 21%, comparable to the state of the art organic and quantum dot LEDs. For metal halide perovskites, their simple solution-processing preparation, facile band gap tunability, and narrow emission line width provide another attractive route to harness their superior optoelectronic properties for multicolor display applications. In this work, we demonstrate a high-resolution, large-scale photolithographic method to pattern multicolor perovskite films. This approach is based on a dry lift-off process which involves the use of parylene as an intermediary and the easy mechanical peeling-off of parylene films on various substrates. Using this approach, we successfully fabricated multicolor patterns with red and green perovskite pixels on a single substrate, which could be further applied in liquid crystal displays (LCDs) with blue backlight. Besides, a prototype green perovskite micro-LED display under current driving has been demonstrated.
100 citations
TL;DR: In this paper, a series of FIB nanofabrication factors related to the fabrication of 3D nanostructures and devices, including mechanisms, instruments, processes, and typical applications, are systematically summarized and analyzed in detail.
Abstract: The past few decades have witnessed growing research interest in developing powerful nanofabrication technologies for three-dimensional (3D) structures and devices to achieve nano-scale and nano-precision manufacturing. Among the various fabrication techniques, focused ion beam (FIB) nanofabrication has been established as a well-suited and promising technique in nearly all fields of nanotechnology for the fabrication of 3D nanostructures and devices because of increasing demands from industry and research. In this article, a series of FIB nanofabrication factors related to the fabrication of 3D nanostructures and devices, including mechanisms, instruments, processes, and typical applications of FIB nanofabrication, are systematically summarized and analyzed in detail. Additionally, current challenges and future development trends of FIB nanofabrication in this field are also given. This work intends to provide guidance for practitioners, researchers, or engineers who wish to learn more about the FIB nanofabrication technology that is driving the revolution in 3D nanostructures and devices.
88 citations
TL;DR: The femtosecond (fs)-laser-assisted formation of three-dimensional MHP nanocrystal (NC) patterns with strong blue photoluminescence (PL) inside an oxide glass with high robustness compared with their colloidal process counterparts is demonstrated.
Abstract: The high-precision patterning of metal halide perovskites (MHPs) is of paramount importance for their device application. Here, we demonstrate the femtosecond (fs)-laser-assisted formation of three...
86 citations
TL;DR: This work demonstrated a facile method to fabricate large-scale thin CsPbBr3 SCFs (∼300 nm) on the c-plane sapphire substrate and supplies an arena to boost the optoelectronic applications of Cs PbBr 3 with high performance.
Abstract: Single-crystal perovskites with excellent photophysical properties are considered to be ideal materials for optoelectronic devices, such as lasers, light-emitting diodes and photodetectors. However...
84 citations
References
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TL;DR: Efficient organic-inorganic perovskite light-emitting diodes were made with nanograin crystals that lack metallic lead, which helped to confine excitons and avoid their quenching.
Abstract: Organic-inorganic hybrid perovskites are emerging low-cost emitters with very high color purity, but their low luminescent efficiency is a critical drawback. We boosted the current efficiency (CE) of perovskite light-emitting diodes with a simple bilayer structure to 42.9 candela per ampere, similar to the CE of phosphorescent organic light-emitting diodes, with two modifications: We prevented the formation of metallic lead (Pb) atoms that cause strong exciton quenching through a small increase in methylammonium bromide (MABr) molar proportion, and we spatially confined the exciton in uniform MAPbBr3 nanograins (average diameter = 99.7 nanometers) formed by a nanocrystal pinning process and concomitant reduction of exciton diffusion length to 67 nanometers. These changes caused substantial increases in steady-state photoluminescence intensity and efficiency of MAPbBr3 nanograin layers.
2,295 citations
TL;DR: A perovskite mixed material comprising a series of differently quantum-size-tuned grains that funnels photoexcitations to the lowest-bandgap light-emitter in the mixture functions as charge carrier concentrators, ensuring that radiative recombination successfully outcompetes trapping and hence non-radiatives recombination.
Abstract: Organometal halide perovskites exhibit large bulk crystal domain sizes, rare traps, excellent mobilities and carriers that are free at room temperature-properties that support their excellent performance in charge-separating devices. In devices that rely on the forward injection of electrons and holes, such as light-emitting diodes (LEDs), excellent mobilities contribute to the efficient capture of non-equilibrium charge carriers by rare non-radiative centres. Moreover, the lack of bound excitons weakens the competition of desired radiative (over undesired non-radiative) recombination. Here we report a perovskite mixed material comprising a series of differently quantum-size-tuned grains that funnels photoexcitations to the lowest-bandgap light-emitter in the mixture. The materials function as charge carrier concentrators, ensuring that radiative recombination successfully outcompetes trapping and hence non-radiative recombination. We use the new material to build devices that exhibit an external quantum efficiency (EQE) of 8.8% and a radiance of 80 W sr-1 m-2. These represent the brightest and most efficient solution-processed near-infrared LEDs to date.
1,756 citations
TL;DR: A reversible photo-induced instability has been found in mixed-halide photovoltaic perovskites that limits the open circuit voltage in solar cells.
Abstract: We report on reversible, light-induced transformations in (CH3NH3)Pb(BrxI1−x)3. Photoluminescence (PL) spectra of these perovskites develop a new, red-shifted peak at 1.68 eV that grows in intensity under constant, 1-sun illumination in less than a minute. This is accompanied by an increase in sub-bandgap absorption at ∼1.7 eV, indicating the formation of luminescent trap states. Light soaking causes a splitting of X-ray diffraction (XRD) peaks, suggesting segregation into two crystalline phases. Surprisingly, these photo-induced changes are fully reversible; the XRD patterns and the PL and absorption spectra revert to their initial states after the materials are left for a few minutes in the dark. We speculate that photoexcitation may cause halide segregation into iodide-rich minority and bromide-enriched majority domains, the former acting as a recombination center trap. This instability may limit achievable voltages from some mixed-halide perovskite solar cells and could have implications for the photostability of halide perovskites used in optoelectronics.
1,549 citations
"Patterning Multicolor Hybrid Perovs..." refers methods in this paper
...These methods could be combined with the lithography process described in this work to achieve multicolor patterns of perovskite nanoparticles on a large scale; however this method is less effective when working with bulk perovskite films because phase separation of the halides can result in unstable and poor quality photoluminescence.(32) Hence a method for achieving a multicolor film from two separate solutions of completely different composition is an important challenge....
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TL;DR: Perovskite quantum wells yield highly efficient LEDs spanning the visible and near-infrared as discussed by the authors. But their performance is not as good as those of traditional LEDs, and their lifetime is shorter.
Abstract: Perovskite quantum wells yield highly efficient LEDs spanning the visible and near-infrared.
1,419 citations
TL;DR: In this article, the authors show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors.
Abstract: Despite the widespread use of solution-processable hybrid organic-inorganic perovskites in photovoltaic and light-emitting applications, determination of their intrinsic charge transport parameters has been elusive due to the variability of film preparation and history-dependent device performance. Here we show that screening effects associated to ionic transport can be effectively eliminated by lowering the operating temperature of methylammonium lead iodide perovskite (CH3NH3PbI3) field-effect transistors. Field-effect carrier mobility is found to increase by almost two orders of magnitude below 200 K, consistent with phonon scattering-limited transport. Under balanced ambipolar carrier injection, gate-dependent electroluminescence is also observed from the transistor channel, with spectra revealing the tetragonal to orthorhombic phase transition. This demonstration of CH3NH3PbI3 light-emitting field-effect transistors provides intrinsic transport parameters to guide materials and solar cell optimization, and will drive the development of new electro-optic device concepts, such as gated light-emitting diodes and lasers operating at room temperature.
550 citations