The demonstration of colour tunability and high efficiency has brought organic light‐emitting diodes (OLEDs) into the displays and lighting market. However, high production costs due to expensive ...deposition techniques and the use of reactive materials still limit their market entry, highlighting the need for novel concepts. This has driven the research towards the integration of both organic and inorganic materials into devices that benefit from their respective peculiar properties. The most representative example of this tendency is the application of metal oxides in organic optoelectronics. Metal oxides combine properties such as high transparency, good electrical conductivities, tuneable morphology, and the possibility of deposition on large areas with low‐cost techniques. The use of metal oxides as charge injection interfaces in OLEDs has also been investigated. Hybrid organic–inorganic light‐emitting diodes (HyLEDs) are inverted OLEDs that employ air‐stable metal oxides as the charge injection contacts. They are emerging as a potential competitor to standard OLEDs, thanks to their intrinsic air stable electrodes and solution processability, which could result in low‐cost, large area, light‐emitting devices. This article reviews the short history of this class of devices from its first solid state example published in 2006 to the present achievements. The data presented shed light on the electronic mechanism behind the functioning of HyLEDs and give guidelines for their further optimization.
Hybrid organic–inorganic light‐emitting diodes (HyLEDs) employ solution‐processable and air‐stable metal oxides as charge injecting contacts. In this article, the recent achievements in understanding and performance are reviewed, demonstrating the potential of HyLEDs for future lighting and displays applications.
Nontoxic alternatives to lead halide perovskites are highly sought after for applications in optoelectronics. Blue-luminescent materials are especially demanded as they could be used to prepare white ...light-emitting diodes, with important potential applications in lighting systems. However, wide band gap blue emitters with high photoluminescence quantum yields (PLQYs) are typically more difficult to obtain as compared to green- or red-emitting ones. Here, we prepared two series of inorganic cesium copper halides, with the general formulas Cs3Cu2X5 and CsCu2X3 (X = Cl, Br, I, and mixtures thereof) by dry mechanochemical synthesis at room temperature. X-ray diffraction demonstrates quantitative conversion of binary precursors into the desired ternary structures and good halide mixing in single-phase compounds. We identified Cs3Cu2I5 as the most promising material as it maintains blue luminescence centered at 442 nm with a high PLQY (>40%) after several days in air (Cs3Cu2Cl5 shows significantly higher PLQY, over 80% but is unstable in air). Based on this, we fabricated homogeneous and pinhole-free Cs3Cu2I5 thin films by thermal single-source vacuum deposition. Crystalline phase and photoluminescence features are maintained in the thin films, demonstrating that these low-toxicity materials can be synthesized and processed by fully solvent-free routes for a widespread implementation in optoelectronic devices.
The diode behavior of photovoltaic devices based on methylammonium lead iodide (MAPbI3) perovskites is examined, in combination with electroluminescence measurements. From this analysis the diode ...ideality factors are extracted, which indicate that non‐radiative trap‐assisted recombination is the dominant recombination pathway, primarily caused by the presence of electron traps.
Mechanochemical synthesis has recently emerged as a promising route for the synthesis of functional lead halide perovskites as well as other (lead‐free) metal halides. Mechanochemical synthesis ...presents several advantages with regards to more commonly used solution‐based processes such as an inherent lower toxicity by avoiding organic solvents and a finer control over stoichiometry of the final products. The ease of implementation, either through the use of a simple mortar and pestle or with an electrically powered ball‐mill, and low amount of side products make mechanochemical synthesis appealing for upscaling the production of halide perovskites. Due to the defect tolerance of lead halide perovskites, they are ideally suited to be prepared by this solvent‐free method. However, the implementation of these semiconductors in high‐efficiency optoelectronic devices requires the transformation of synthesized powder into smooth thin films where still some hurdles remain to be cleared.
Mechanochemistry has recently reemerged as a promising green‐chemistry approach for the development of lead halide perovskites and related materials. Simple grinding of halide precursors yields phase‐pure multinary metal halides with excellent optoelectronic properties within minutes. Recent examples of their implementation in high‐efficiency devices are described, alongside promising single‐source vacuum deposition methods for fully solvent‐free processing.
The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for ...Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.14 V closer to its radiative limit than the OPV cell. Additionally, and in contrast to OPVs, we show that the photoluminescence of the perovskite solar cell is substantially quenched under short circuit conditions in accordance with how an ideal photovoltaic cell should operate.
To date, there is no example in the literature of free, nanometer-sized, organolead halide CH3NH3PbBr3 perovskites. We report here the preparation of 6 nm-sized nanoparticles of this type by a simple ...and fast method based on the use of an ammonium bromide with a medium-sized chain that keeps the nanoparticles dispersed in a wide range of organic solvents. These nanoparticles can be maintained stable in the solid state as well as in concentrated solutions for more than three months, without requiring a mesoporous material. This makes it possible to prepare homogeneous thin films of these nanoparticles by spin-coating on a quartz substrate. Both the colloidal solution and the thin film emit light within a narrow bandwidth of the visible spectrum and with a high quantum yield (ca. 20%); this could be advantageous in the design of optoelectronic devices.
Higher efficiency in the end‐use of energy requires substantial progress in lighting concepts. All the technologies under development are based on solid‐state electroluminescent materials and belong ...to the general area of solid‐state lighting (SSL). The two main technologies being developed in SSL are light‐emitting diodes (LEDs) and organic light‐emitting diodes (OLEDs), but in recent years, light‐emitting electrochemical cells (LECs) have emerged as an alternative option. The luminescent materials in LECs are either luminescent polymers together with ionic salts or ionic species, such as ionic transition‐metal complexes (iTMCs). Cyclometalated complexes of IrIII are by far the most utilized class of iTMCs in LECs. Herein, we show how these complexes can be prepared and discuss their unique electronic, photophysical, and photochemical properties. Finally, the progress in the performance of iTMCs based LECs, in terms of turn‐on time, stability, efficiency, and color is presented.
LECtric lighting: The expansion of artificial illumination and the need for more efficient appliances is stimulating innovative lighting concepts. Light‐emitting electrochemical cells (LECs) based on luminescent transition‐metal complexes (see picture) stand out as promising devices for lighting panels, thanks to recent advances in their design, driving conditions, and their overall performance.
Advances in Perovskite Solar Cells Zuo, Chuantian; Bolink, Henk J.; Han, Hongwei ...
Advanced science,
July 2016, Letnik:
3, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Organolead halide perovskite materials possess a combination of remarkable optoelectronic properties, such as steep optical absorption edge and high absorption coefficients, long charge carrier ...diffusion lengths and lifetimes. Taken together with the ability for low temperature preparation, also from solution, perovskite‐based devices, especially photovoltaic (PV) cells have been studied intensively, with remarkable progress in performance, over the past few years. The combination of high efficiency, low cost and additional (non‐PV) applications provides great potential for commercialization. Performance and applications of perovskite solar cells often correlate with their device structures. Many innovative device structures were developed, aiming at large‐scale fabrication, reducing fabrication cost, enhancing the power conversion efficiency and thus broadening potential future applications. This review summarizes typical structures of perovskite solar cells and comments on novel device structures. The applications of perovskite solar cells are discussed.
Perovskite solar cells have been advancing rapidly as a new photovoltaic technology. Device structures have been evolving, demonstrating outstanding performance due to the extraordinary optical and electronic features of organolead halide perovskite materials. Typical structures and promising applications of perovskite solar cells are summarized and discussed. This technology appears to be well positioned for commercialization.
PDF
