Recently, perovskites with multiple cations, metals, and anions have shown very high efficiencies and stabilities for perovskite solar cells. The novel materials frequently exhibit unexpected and ...beneficial properties, outperforming simpler counterparts. The trend of increasing material complexity requires a systematic strategy to explore polyelemental “multicomponent engineering.” Here, a combinatorial approach is introduced to generate all possible, unique combinations within a set of available components. Thus, with each new component, the combinatorial framework can generate the full theoretical parameter space. Based on reported components, the experimental parameter space can then be identified. The exceptional material versatility of perovskites is suited for high‐throughput screening, machine‐learning, or data mining, laying the foundation for a “perovskite genome project” that thoroughly catalogues the entire material family for desired properties. This can provide the framework for theoretical simulations toward understanding the fundamental working principles of perovskite materials enabling the “next big thing” after perovskites. Finally, informed by literature, a promising candidate list for future material exploration is presented including novel organic‐free, Pb‐free, and all‐inorganic perovskites. These compounds are primary contenders toward stable, high efficiency, and reproducible materials for rapid industrialization of perovskite solar cells, lasers, light‐emitting diodes, photo detectors, or particle detectors.
Exceptionally versatile, polyelemental perovskites are suited for high‐throughput screening, machine‐learning, or data mining. This lays the foundation for a “perovskite genome project” that catalogues the entire material family and provides the framework for theoretical simulations towards a detailed understanding of the fundamental working principles of perovskite materials. This could be the starting point for the “next big thing” after perovskites.
Recently organic–inorganic perovskite solar cells (PSCs) have emerged as promising candidates for photovoltaics because of their relatively high efficiency and low processing costs. However, for ...possible commercialisation, long-term stability remains a key obstacle, especially when compared to silicon or GaAs. Thus, future research will significantly focus on stability. The most relevant industry standards for the stability of solar cells are issued by the International Electrotechnical Commission (IEC), summarized in the so-called IEC 61215 norm. The IEC 61215 is a series of very detailed, time-consuming and interconnected stress tests that provide accelerated aging conditions to extrapolate the potential long-term lifetime of a solar module. Established silicon, for example, passes the full IEC 61215. To gain the confidence of investors and customers, passing the full IEC 61215 is a necessary minimum requirement for the commercialization of perovskites. Interestingly, the IEC 61215 is not openly accessible which may be one reason why there are often references to outdated versions. To remedy this situation, we introduce and analyse the most current IEC 61215 stability standards for solar cells and to which degree perovskites have passed them. We then elaborate on the most pertinent challenges for the long-term stability of PSCs in the coming years. This includes less explored stability tests such as potential-induced degradation (IEC TS 62804-1) and ammonia corrosion (IEC 62716). From this, it is evident that currently underappreciated degradation modes such as mechanical stability, high applied voltages and reverse bias, where especially hot spots could become problematic, must be considered in the coming years when evaluating the long-term stability of PSCs.
Currently, perovskite solar cells (PSCs) with high performances greater than 20% contain bromine (Br), causing a suboptimal bandgap, and the thermally unstable methylammonium (MA) molecule. Avoiding ...Br and especially MA can therefore result in more optimal bandgaps and stable perovskites. We show that inorganic cation tuning, using rubidium and cesium, enables highly crystalline formamidinium-based perovskites without Br or MA. On a conventional, planar device architecture, using polymeric interlayers at the electron- and hole-transporting interface, we demonstrate an efficiency of 20.35% (stabilized), one of the highest for MA-free perovskites, with a drastically improved stability reached without the stabilizing influence of mesoporous interlayers. The perovskite is not heated beyond 100°C. Going MA-free is a new direction for perovskites that are inherently stable and compatible with tandems or flexible substrates, which are the main routes commercializing PSCs.
Organic–inorganic perovskites have made tremendous progress in recent years due to exceptional material properties such as high panchromatic absorption, charge carrier diffusion lengths, and a sharp ...optical band edge. The combination of high‐quality semiconductor performance with low‐cost deposition techniques seems to be a match made in heaven, creating great excitement far beyond academic ivory towers. This is particularly true for perovskite solar cells (PSCs) that have shown unprecedented gains in efficiency and stability over a time span of just five years. Now there are serious efforts for commercialization with the hope that PSCs can make a major impact in generating inexpensive, sustainable solar electricity. In this Review, we will focus on perovskite material properties as well as on devices from the atomic to the thin film level to highlight the remaining challenges and to anticipate the future developments of PSCs.
Perovskite solar cells have emerged as a low‐cost, thin‐film technology with unprecedented efficiency gains that challenge the quasi‐paradigm that high efficiency photovoltaics must come at high costs. Perovskites can be processed via inexpensive solution methods and have exceptional material properties that are comparable to established materials such as CdTe, GaAs, or Si. Remarkably, perovskites have a continuously tuneable band gap from 1 to 3 eV enabling applications far beyond photovoltaics.
Perovskite solar cells (PSCs) have been introduced as an attractive photovoltaic technology over the past decade due to their low‐cost processing, earth‐abundant raw materials, and high power ...conversion efficiencies (PCEs) of up to 25.2%. However, the relatively high density of defects within the bulk, grain boundaries, and surface of polycrystalline perovskite films acts as recombination centers and facilitates ion migration, lowering the theoretical PCE ceiling, often leading to inferior device stability. Therefore, understanding the defect sources and developing passivation methods are key factors for reaching higher PCEs and stabilities in perovskite photovoltaics. Herein, various passivation methods, including bulk and surface treatment of perovskite films, are explored. In the bulk treatment, the passivating agents should be directly added to the perovskite precursor. However, in the surface treatment method, the surface of perovskite films can be treated by inducing passivating agents during the intermediate phase or after annealing steps, denoted here as in‐film or surface posttreatment. In addition, different kinds of passivating agents are categorized based on their functional groups. Finally, the outline directions to minimize the defects in perovskite films are highlighted.
Herein, perovskite defects are categorized into two big groups of halide and cation vacancies. The defect passivation methods are divided into bulk and surface treatment of perovskite films. All kinds of passivating agent materials are classified based on their functional groups for defect passivation. Finally, a comprehensive perspective for achieving high‐performance and stable perovskite solar cells is provided.
Promises and challenges of perovskite solar cells Correa-Baena, Juan-Pablo; Saliba, Michael; Buonassisi, Tonio ...
Science (American Association for the Advancement of Science),
11/2017, Letnik:
358, Številka:
6364
Journal Article
Recenzirano
Odprti dostop
The efficiencies of perovskite solar cells have gone from single digits to a certified 22.1% in a few years’ time. At this stage of their development, the key issues concern how to achieve further ...improvements in efficiency and long-term stability. We review recent developments in the quest to improve the current state of the art. Because photocurrents are near the theoretical maximum, our focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring. The challenges associated with long-term perovskite solar cell device stability include the role of testing protocols, ionic movement affecting performance metrics over extended periods of time, and determination of the best ways to counteract degradation mechanisms.
Perovskite solar cells (PSCs) have attracted much attention because of their rapid rise to 22% efficiencies. Here, we review the rapid evolution of PSCs as they enter a new phase that could ...revolutionize the photovoltaic industry. In particular, we describe the properties that make perovskites so remarkable, and the current understanding of the PSC device physics, including the operation of state-of-the-art solar cells with efficiencies above 20%. The extraordinary progress of long-term stability is discussed and we provide an outlook on what the future of PSCs might soon bring the photovoltaic community. Some challenges remain in terms of reducing non-radiative recombination and increasing conductivity of the different device layers, and these will be discussed in depth in this review.
The latest developments in the efficiency and long-term stability of perovskite solar cells are summarized.
Organic‐inorganic metal halide perovskite solar cells show hysteresis in their current–voltage curve measured at a certain voltage sweep rate. Coinciding with a slow transient current response, the ...hysteresis is attributed to a slow voltage‐driven (ionic) charge redistribution in the perovskite solar cell. Thus, the electric field profile and in turn the electron/hole collection efficiency become dependent on the biasing history. Commonly, a positive prebias is beneficial for a high power‐conversion efficiency. Fill factor and open‐circuit voltage increase because the prebias removes the driving force for charge to pile‐up at the electrodes, which screen the electric field. Here, it is shown that the piled‐up charge can also be beneficial. It increases the probability for electron extraction in case of extraction barriers due to an enhanced electric field allowing for tunneling or dipole formation at the perovskite/electrode interface. In that case, an inverted hysteresis is observed, resulting in higher performance metrics for a voltage sweep starting at low prebias. This inverted hysteresis is particularly pronounced in mixed‐cation mixed‐halide systems which comprise a new generation of perovskite solar cells that makes it possible to reach power‐conversion efficiencies beyond 20%.
Inverted hysteresis is observed in mixed cation mixed halide perovskite solar cells, which show a power‐conversion efficiency of 20%. It is attributed to charge accumulation and dipole formation at the perovskite/TiO2 interface changing extraction barrier and recombination lifetimes in and close to the mesoporous scaffold.
The presence of bulk and surface defects in perovskite light harvesting materials limits the overall efficiency of perovskite solar cells (PSCs). The formation of such defects is suppressed by adding ...methylammonium chloride (MACl) as a crystallization aid to the precursor solution to realize high‐quality, large‐grain triple A‐cation perovskite films and that are combined with judicious engineering of the perovskite interface with the electron and hole selective contact materials. A planar SnO2/TiO2 double layer oxide is introduced to ascertain fast electron extraction and the surface of the perovskite facing the hole conductor is treated with iodine dissolved in isopropanol to passivate surface trap states resulting in a retardation of radiationless carrier recombination. A maximum solar to electric power conversion efficiency (PCE) of 21.65% and open circuit photovoltage (Voc) of ≈1.24 V with only ≈370 mV loss in potential with respect to the band gap are achieved, by applying these modifications. Additionally, the defect healing enhances the operational stability of the devices that retain 96%, 90%, and 85% of their initial PCE values after 500 h under continuously light illumination at 20, 50, and 65 °C, respectively, demonstrating one of the most stable planar PSCs reported so far.
The bulk and surface defects of perovskite films are suppressed by using SnO2/TiO2 double layer oxide, addition of methylammonium chloride (MACl) as a crystallization aid to the precursor solution, and surface passivation of perovskite films with iodine solution, due to the formation of high‐quality large‐grain perovskite films and retardation of radiationless carrier recombination.
Lead‐halide perovskites (LHPs), in the form of both colloidal nanocrystals (NCs) and thin films, have emerged over the past decade as leading candidates for next‐generation, efficient light‐emitting ...diodes (LEDs) and solar cells. Owing to their high photoluminescence quantum yields (PLQYs), LHPs efficiently convert injected charge carriers into light and vice versa. However, despite the defect‐tolerance of LHPs, defects at the surface of colloidal NCs and grain boundaries in thin films play a critical role in charge‐carrier transport and nonradiative recombination, which lowers the PLQYs, device efficiency, and stability. Therefore, understanding the defects that play a key role in limiting performance, and developing effective passivation routes are critical for achieving advances in performance. This Review presents the current understanding of defects in halide perovskites and their influence on the optical and charge‐carrier transport properties. Passivation strategies toward improving the efficiencies of perovskite‐based LEDs and solar cells are also discussed.
Despite the defect‐tolerance of lead‐halide perovskites, defects at the surface of colloidal nanocrystals and grain boundaries in thin films play a critical role in charge‐carrier transport and nonradiative recombination, which lowers the photoluminescence quantum yields, device efficiency, and stability. This Review summarizes the defects, their influence on the optical and charge‐carrier transport properties, and passivation strategies to mitigate the effects of defects.
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