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A comprehensive algorithm for calculating the energy yield (EY) is used as the most important figure‐of‐merit in determining the capabilities of PV devices in realistic operation. The model is based on advanced optical modeling and extensive opto‐thermo‐electrical characterization. It takes the realistic environmental and device installation data fully into account, as well as the complete set of device specifications including all relevant temperature‐induced variations. A detailed analysis and optimization of two‐terminal perovskite‐silicon tandem devices are done in terms of long‐term electrical energy production at different geographical locations from distinct Köppen–Geiger–Photovoltaic climate zones (KGPV). It is shown that the optimal perovskite bandgap (EG,PK) in a tandem device operating under realistic conditions is in all cases higher than the one optimized under STC, yet does not differ significantly from location to location, which is beneficial from the manufacturing point of view. The optimal EG,PK is influenced primarily by the spectral distribution of incident irradiance, and not so much by the operating temperature conditions. Moreover, a clear linear dependency between the optimal EG,PK and the weighted average photon energy of the incident irradiance is demonstrated, which presents an important rule for rapid tandem design. [ABSTRACT FROM AUTHOR]

Advanced concepts of optical modelling present one of the key tools for analysis, design and optimization of modern optoelectronic devices, such as solar cells and light-emitting diodes. However, since the structures of these devices are becoming increasingly more complex, they can only be accurately treated by means of a coupled modelling approach, in which different parts of the device are analyzed by different numerical models. In this work, we focus on coupled optical modelling of high-efficiency heterojunction silicon solar cells and organic light-emitting diodes. Employing optical simulations in both cases, we first analyze the performance of the initial device structures, with a special emphasis on the analysis of optical losses. Then both devices are enhanced with a surface-textured light-management foil at the front side by which the in-coupling into the solar cell and the out-coupling out of the light-emitting diode are improved significantly. We evaluate the performance of the surface-textured devices compared to their initial structure. In the final part, we optimize the geometrical profile of the surface texture to obtain an optimal device performance in both types of the studied optoelectronic devices. [ABSTRACT FROM AUTHOR]

Tandem solar cells are the next step in the photovoltaic (PV) evolution due to their higher power conversion efficiency (PCE) potential than currently dominating, but inherently limited, single‐junction solar cells. With the emergence of metal halide perovskite absorber materials, the fabrication of highly efficient tandem solar cells, at a reasonable cost, can significantly impact the future PV landscape. The perovskite‐based tandem solar cells have already shown that they can convert light more efficiently than their standalone sub‐cells. However, to reach PCEs over 30%, several challenges have to be overcome and the understanding of this fascinating technology has to be broadened. In this review, the main scientific and engineering challenges in the field are presented, alongside a discussion of the current status of three main perovskite tandem technologies: perovskite/silicon, perovskite/CIGS, and perovskite/perovskite tandem solar cells. A summary of the advanced structural, electrical, optical, radiative, and electronic characterization methods as well as simulations being utilized for perovskite‐based tandem solar cells is presented. The main findings are summarized and the strength of the techniques to overcome the challenges and gain deeper knowledge for further performance improvement is assessed. Finally, the PCE potential in different experimental and theoretical limits is compared with an aim to shed light on the path towards overcoming the 30% efficiency threshold for all of the three herein reviewed tandem technologies. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSC) have shown that under laboratory conditions they can compete with established photovoltaic technologies. However, controlled laboratory measurements usually performed do not fully resemble operational conditions and field testing outdoors, with day‐night cycles, changing irradiance and temperature. In this contribution, the performance of PSCs in the rooftop field test, exposed to real weather conditions is evaluated. The 1 cm2 single‐junction devices, with an initial average power conversion efficiency of 18.5% are tracked outdoors in maximum power point over several weeks. In parallel, irradiance and air temperature are recorded, allowing us to correlate outside factors with generated power. To get more insight into outdoor device performance, a comprehensive set of laboratory measurements under different light intensities (10% to 120% of AM1.5) and temperatures is performed. From these results, a low power temperature coefficient of −0.17% K−1 is extracted in the temperature range between 25 and 85 °C. By incorporating these temperature‐ and light‐dependent PV parameters into the energy yield model, it is possible to correctly predict the generated energy of the devices, thus validating the energy yield model. In addition, degradation of the tested devices can be tracked precisely from the difference between measured and modelled power. [ABSTRACT FROM AUTHOR]

Perovskite solar cells are a novel class of photovoltaic materials that have attracted a lot of attention due to their excellent optoelectronic properties, simplicity and potential low manufacture cost. Perovskite solar cells are often used as a top cell in perovskite/silicon tandem solar cells. There optics play a crucial role in determining the device performance. Our optical simulations of the tandem solar cells show that the C60 layer, i. e. the most common electron transport layer used in the perovskite solar cells, has to be as thin as possible to minimize its high parasitic absorption. However, a certain thickness of the C60 layer is still needed to ensure good electrical performance. The paper analyzes the effect of the C60 layer thickness on the device performance using single-junction perovskite solar cells that enable an easier and more reproducible analysis. It is shown that the minimal C60 layer thickness needed for efficient solar cells with high fill factor is 15 nm. The power conversion efficiency of so fabricated devices is 19%. [ABSTRACT FROM AUTHOR]

Accurate forecasting of yearly energy yield of photovoltaic devices under realistic operating conditions is key for numerous practical applications related to further evolution of photovoltaics. In this work we present development and validation of an energy yield model applied to planar perovskite solar cells. The model is based on the combination of advanced optical modelling and extensive opto-electrical characterization and takes the geographical location and the orientation of the device into account. Using the model, we first perform a detailed sensitivity analysis and indicate the key parameters and their interdependencies that most significantly affect the calculated energy yield values. We show that the results are dominated (within 4% of the final value) by the solar irradiance dependency of the short-circuit current density, and further by the temperature dependency of the open-circuit voltage and the fill factor, whereas the irradiance dependency of the open-circuit voltage and the fill factor are mutually compensated. In the second part of the paper, we investigate how the energy yield of the device is affected by the application of external light management foils. Different texture morphologies, geographical locations, and device orientations are included in the investigation. The results show that even under realistic operating conditions, the overall trends of the light management efficiency of textured foils are not that different from those observed under standard test conditions; the highest energy yield gains in the order of 7–11% are obtained by the tetrahedral texture which is indicated as optimal in all studied cases. [Display omitted] • EY forecasting crucial for LCOE estimation, degradation monitoring, and device optimization. • J SC under realistic conditions can be simulatend using advanced optical modelling. • V OC and FF under realistic conditions can be obtained through extensive electrical characterization. • External light management foils provide significant EY boosts under realistic outdoor conditions; tetrahedral micro texture indicated as the optimal in all studied cases. • Similar trends observed as under STC conditions, with similar achievable relative gains. [ABSTRACT FROM AUTHOR]

Perovskite‐based solar cells exhibit peculiar outdoor performance which is not yet fully understood. The results of outdoor tests may contain hidden, but valuable information that cannot be fully extracted from measurements alone. One such phenomenon is the effect of nighttime degradation and the subsequent light‐soaking recovery, which can take from a few hours in the morning up to the entire day. In this work, long‐term outdoor monitoring is combined with energy yield modeling to qualitatively and quantitatively investigate the effect of light‐soaking recovery in both single junction and tandem perovskite‐based devices. Following the novel methodology presented in this study, it is observed that the light‐soaking effect depends not only on the daily irradiation but also on the device temperature, and it can be described using a simple empirical formalism. Incorporating this dependency into the energy yield model results in an excellent agreement between the simulated and the measured outdoor data, which allows to perform long‐term prediction studies. The model estimates that the light‐soaking metastability effect decreases the attainable annual energy yield by up to ≈5% for the studied single junction devices, and for tandems by up to ≈3%, depending on the geographical location, and even more for non‐optimal device orientation. [ABSTRACT FROM AUTHOR]

Tandem solar cells that pair silicon with a metal halide perovskite are a promising option for surpassing the single-cell efficiency limit. We report a monolithic perovskite/silicon tandem with a certified power conversion efficiency of 29.15%. The perovskite absorber, with a bandgap of 1.68 electron volts, remained phase-stable under illumination through a combination of fast hole extraction and minimized nonradiative recombination at the hole-selective interface. These features were made possible by a self-assembled, methyl-substituted carbazole monolayer as the hole-selective layer in the perovskite cell. The accelerated hole extraction was linked to a low ideality factor of 1.26 and single-junction fill factors of up to 84%, while enabling a tandem open-circuit voltage of as high as 1.92 volts. In air, without encapsulation, a tandem retained 95% of its initial efficiency after 300 hours of operation. [ABSTRACT FROM AUTHOR]

The structural phases and optoelectronic properties of coevaporated CsPbI3 thin films with a wide range of [CsI]/[PbI2] compositional ratios are investigated using high throughput experimentation and gradient samples. It is found that for CsI‐rich growth conditions, CsPbI3 can be synthesized directly at low temperature into the distorted perovskite γ‐CsPbI3 phase without detectable secondary phases. In contrast, PbI2‐rich growth conditions are found to lead to the non‐perovskite δ‐phase. Photoluminescence spectroscopy and optical‐pump THz‐probe mapping show carrier lifetimes larger than 75 ns and charge carrier (sum) mobilities larger than 60 cm2 V−1 s−1 for the γ‐phase, indicating their suitability for high efficiency solar cells. The dependence of the carrier mobilities and luminescence peak energy on the Cs‐content in the films indicates the presence of Schottky defect pairs, which may cause the stabilization of the γ‐phase. Building on these results, p–i–n type solar cells with a maximum efficiency exceeding 12% and high shelf stability of more than 1200 h are demonstrated, which in the future could still be significantly improved, judging on their bulk optoelectronic properties. [ABSTRACT FROM AUTHOR]

In article number 1801892, Steve Albrecht, Vytautas Getautis and co‐workers demonstrate a novel promising concept for the formation of a hole selective monolayer in perovskite solar cells. A low temperature dopant‐free technique makes it suitable for different substrates. [ABSTRACT FROM AUTHOR]

The unprecedented emergence of perovskite‐based solar cells (PSCs) has been accompanied by an intensive search of suitable materials for charge‐selective contacts. For the first time a hole‐transporting self‐assembled monolayer (SAM) as the dopant‐free hole‐selective contact in p–i–n PSCs is used and a power conversion efficiency of up to 17.8% with average fill factor close to 80% and undetectable parasitic absorption is demonstrated. SAM formation is achieved by simply immersing the substrate into a solution of a novel molecule V1036 that binds to the indium tin oxide surface due to its phosphonic anchoring group. The SAM and its modifications are further characterized by Fourier‐transform infrared and vibrational sum‐frequency generation spectroscopy. In addition, photoelectron spectroscopy in air is used for measuring the ionization potential of the studied SAMs. This novel approach is also suitable for achieving a conformal coverage of large‐area and/or textured substrates with minimal material consumption and can potentially be extended to serve as a model system for substrate‐based perovskite nucleation and passivation control. Further gains in efficiency can be expected upon SAM optimization by means of molecular and compositional engineering. A novel concept for the formation of the hole selective layer in efficient perovskite solar cells is presented. Carbazole‐based material is synthesized and used for the formation of a self‐assembled monolayer on top of the indium tin oxide transparent conductive substrate. Power conversion efficiency as high as 17.8% is achieved. [ABSTRACT FROM AUTHOR]