Deposition of perovskite films by antisolvent engineering is a highly common method employed in perovskite photovoltaics research. Herein, we report on a general method that allows for the ...fabrication of highly efficient perovskite solar cells by any antisolvent via manipulation of the antisolvent application rate. Through detailed structural, compositional, and microstructural characterization of perovskite layers fabricated by 14 different antisolvents, we identify two key factors that influence the quality of the perovskite layer: the solubility of the organic precursors in the antisolvent and its miscibility with the host solvent(s) of the perovskite precursor solution, which combine to produce rate-dependent behavior during the antisolvent application step. Leveraging this, we produce devices with power conversion efficiencies (PCEs) that exceed 21% using a wide range of antisolvents. Moreover, we demonstrate that employing the optimal antisolvent application procedure allows for highly efficient solar cells to be fabricated from a broad range of precursor stoichiometries.
Lead halide perovskites are a remarkable class of materials that have emerged over the past decade as being suitable for application in a broad range of devices, such as solar cells, light‐emitting ...diodes, lasers, transistors, and memory devices. While they are often solution‐processed semiconductors deposited at low temperatures, perovskites exhibit properties one would only expect from highly pure inorganic crystals that are grown at high temperatures. This unique phenomenon has resulted in fast‐paced progress toward record device performance. Unfortunately, the basic science behind the remarkable nature of these materials is still not well understood. This review assesses the current understanding of the photoluminescence properties of metal halide perovskite materials and highlights key areas that require further research. Furthermore, the need to standardize the methods for characterization of PL in order to improve comparability, reliability, and reproducibility of results is emphasized.
The study of the photoluminescence properties of metal halide perovskites is of great importance for both the fundamental understanding of their photophysics and further optimization of perovskite‐based optoelectronic devices. This review provides an overview of the current state of knowledge related to the photoluminescence of perovskites and highlights the dire need for standardization of characterization methodologies in order to improve the reproducibility, reliability, and comparability of results.
The last decade has seen remarkable advancements in the field of perovskite materials and photovoltaic technologies. One of their most extraordinary characteristics is the high quality of layers that ...can be obtained by “dirty processing” from solution at low temperatures. Alternatively, perovskites can also be deposited by thermal evaporation, a clean, solvent‐free process, which is well established for many industrial applications. Although the vast majority of research reports focus on solution‐processing as the deposition method for perovskite solar cells, thermally evaporated perovskite solar cells are closing in the performance gap with several reports of efficiencies above 20%. In this Progress Report, the two deposition methods are briefly introduced, the key developments in photovoltaic devices based on each deposition technique are outlined, and the challenges and future possibilities are discussed.
The capability to deposit perovskite materials by either thermal evaporation or solution processing offers intriguing possibilities for mass production of perovskite solar cells. This Progress Report describes the current state of research in both fields, discusses the challenges faced by these methods and their future opportunities.
Metal halide perovskites are an important class of emerging semiconductors. Their charge carrier dynamics is poorly understood due to limited knowledge of defect physics and charge ...carrier recombination mechanisms. Nevertheless, classical ABC and Shockley-Read-Hall (SRH) models are ubiquitously applied to perovskites without considering their validity. Herein, an advanced technique mapping photoluminescence quantum yield (PLQY) as a function of both the excitation pulse energy and repetition frequency is developed and employed to examine the validity of these models. While ABC and SRH fail to explain the charge dynamics in a broad range of conditions, the addition of Auger recombination and trapping to the SRH model enables a quantitative fitting of PLQY maps and low-power PL decay kinetics, and extracting trap concentrations and efficacies. However, PL kinetics at high power are too fast and cannot be explained. The proposed PLQY mapping technique is ideal for a comprehensive testing of theories and applicable to any semiconductor.
Field‐effect transistors (FETs) are key elements in modern electronics and hence are attracting immense scientific and commercial attention. The recent emergence of metal halide perovskite materials ...and their tremendous success in the field of photovoltaics have triggered the exploration of their application in other (opto)electronic devices, including FETs and phototransistors. In this review, the current status of the field is discussed, the challenges are highlighted, and an outlook for the future perspectives of perovskite FETs is provided. First, attention is drawn to the device physics and the fundamental processes that influence these devices, including the role of ion migration and defects, effects of temperature, light, and measurement conditions. Next, the performance of perovskite transistors and phototransistors reported to date are surveyed and critically assessed. Finally, the key challenges that impede perovskite transistor progress are outlined and discussed. The insights gained from the study of other perovskite optoelectronic devices may be adopted to address these challenges and advance this exciting field of research closer to the industrial application are examined.
The development of metal halide perovskite field‐effect transistors (FETs) and phototransistors is vital for advancing perovskite electronics. This review introduces the unique physics of perovskite FETs, explores the recent progress in the field, and outlines the key challenges and opportunities that lie ahead of this emerging electronic technology.
Despite remarkable progress, the performance of lead halide perovskite solar cells fabricated in an inverted structure lags behind that of standard architecture devices. Here, we report on a dual ...interfacial modification approach based on the incorporation of large organic cations at both the bottom and top interfaces of the perovskite active layer. Together, this leads to a simultaneous improvement in both the open-circuit voltage and fill factor of the devices, reaching maximum values of 1.184 V and 85%, respectively, resulting in a champion device efficiency of 23.7%. This dual interfacial modification is fully compatible with a bulk modification of the perovskite active layer by ionic liquids, leading to both efficient and stable inverted architecture devices.
Interface engineering through passivating agents, in the form of organic molecules, is a powerful strategy to enhance the performance of perovskite solar cells. Despite its pivotal function in the ...development of a rational device optimization, the actual role played by the incorporation of interfacial modifications and the interface physics therein remains poorly understood. Here, we investigate the interface and device physics, quantifying charge recombination and charge losses in state-of-the-art inverted solar cells with power conversion efficiency beyond 23% - among the highest reported so far - by using multidimensional photoluminescence imaging. By doing that we extract physical parameters such as quasi-Fermi level splitting (QFLS) and Urbach energy enabling us to assess that the main passivation mechanism affects the perovskite/PCBM (6,6-phenyl-C
-butyric acid methyl ester) interface rather than surface defects. In this work, by linking optical, electrical measurements and modelling we highlight the benefits of organic passivation, made in this case by phenylethylammonium (PEAI) based cations, in maximising all the photovoltaic figures of merit.
The last five years have witnessed remarkable progress in the field of lead halide perovskite materials and devices. Examining the existing body of literature reveals staggering inconsistencies in ...the reported results among different research groups with a particularly wide spread in the photovoltaic performance and stability of devices. In this work we demonstrate that fractional, quite possibly unintentional, deviations in the precursor solution stoichiometry can cause significant changes in the properties of the perovskite layer as well as in the performance and stability of perovskite photovoltaic devices. We show that while the absorbance and morphology of the layers remain largely unaffected, the surface composition and energetics, crystallinity, emission efficiency, energetic disorder and storage stability are all very sensitive to the precise stoichiometry of the precursor solution. Our results elucidate the origin of the irreproducibility and inconsistencies of reported results among different groups as well as the wide spread in device performance even within individual studies. Finally, we propose a simple experimental method to identify the exact stoichiometry of the perovskite layer that researchers can employ to confirm their experiments are performed consistently without unintentional variations in precursor stoichiometry.
The migration and accumulation of iodide ions create a modulation of the respective interfacial barriers causing the hysteresis in solar cells based on methylammonium lead iodide perovskites. Iodide ...ions are identified as the migrating species by measuring temperature dependent current‐transients and photoelectron spectroscopy. The involved changes in the built‐in potential due to ion migration are directly measured by electroabsorption spectroscopy.
In spintronics, pure spin currents play a key role in transmitting, processing and storing information. A pure spin current is a ow of electron spin angular momentum without a simultaneous ow of ...charge current. It can be carried by conduction electrons or magnons and has been studied in many inorganic metals, semiconductors and insulators, but not yet in organic semiconductors. Charge carriers in -conjugated organic materials are localized spin-1/2 polarons which move by hopping, but the mechanisms of their spin transport and relaxation are not well understood. Here the authors use ferromagnetic resonance spin pumping in a ferromagnet/conjugated polymer/nonmagnetic spin-sink trilayer to demonstrate the ability of polarons to carry pure spin currents over hundreds of nanometres with long spin relaxation times of up to a millisecond and to exhibit Hanle precession. By systematically comparing charge and spin transport on the same trilayer we show that spin-orbit coupling mediates spin relaxation at room temperature.
PDF
