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The steadily growing market share of building‐integrated photovoltaics (BIPVs) places the aesthetics of solar modules in the focus of research and development. In this work, a colorization method based on inkjet‐printed reflective pigments is adapted for the emerging perovskite photovoltaics. Herein, not only excellent control of color impression, brightness, and pattern is demonstrated, but also angle invariant color perception, which makes the presented approach stand out among the many published colorization strategies for perovskite solar cells (PSCs). Compared to uncolored reference solar cells, bright magenta and yellow PSCs display a remarkable relative power conversion efficiency (PCE) of up to 65% and more than 11% absolute PCE. Moreover, PSCs with more BIPV‐relevant coloring patterns such as a mimic of a marble or corten steel surfaces are demonstrated. The colorization method presented is inexpensive and ready for scalable solar module production. To demonstrate the scalability of the proposed concept, a small‐area perovskite solar module (4 cm2 aperture area) in white marble optics exhibiting a PCE of almost 14% as a potential application is presented. [ABSTRACT FROM AUTHOR]

Given the outstanding progress in research over the past decade, perovskite photovoltaics (PV) is about to step up from laboratory prototypes to commercial products. For this to happen, realizing scalable processes to allow the technology to transition from solar cells to modules is pivotal. This work presents all‐evaporated perovskite PV modules with all thin films coated by established vacuum deposition processes. A common 532‐nm nanosecond laser source is employed to realize all three interconnection lines of the solar modules. The resulting module interconnections exhibit low series resistance and a small total lateral extension down to 160 μm. In comparison with interconnection fabrication approaches utilizing multiple scribing tools, the process complexity is reduced while the obtained geometrical fill factor of 96% is comparable with established inorganic thin‐film PV technologies. The all‐evaporated perovskite minimodules demonstrate power conversion efficiencies of 18.0% and 16.6% on aperture areas of 4 and 51 cm2, respectively. Most importantly, the all‐evaporated minimodules exhibit only minimal upscaling losses as low as 3.1%rel per decade of upscaled area, at the same time being the most efficient perovskite PV minimodules based on an all‐evaporated layer stack sequence. [ABSTRACT FROM AUTHOR]

Vacuum-based deposition of optoelectronic thin films has a long-standing history. However, in the field of perovskite-based photovoltaics, these techniques are still not as advanced as their solution-based counterparts. Although high-efficiency vacuum-based perovskite solar cells reaching power conversion efficiencies (PCEs) above 20% are reported, the number of studies on the underlying physical and chemical mechanism of the co-evaporation of lead iodide and methylammonium iodide is low. In this study, the impact of one of the most crucial process parameters in vacuum processes--the substrate material--is studied. It is shown that not only the morphology of the co-evaporated perovskite thin films is significantly influenced by the surface polarity of the substrate material, but also the incorporation of the organic compound into the perovskite framework. Based on these studies, a selection guide for suitable substrate materials for efficient co-evaporated perovskite thin films is derived. This selection guide points out that the organic vacuum-processable hole transport material 2,2�€�,7,7�€�-tet ra(N,N-di-p-tolyl)amino-9,9-spirobifluorene is an ideal candidate for the fabrication of efficient all-evaporated perovskite solar cells, demonstrating PCEs above 19%. Furthermore, building on the insights into the formation of the perovskite thin films on different substrate materials, a basic crystallization model for co-evaporated perovskite thin films is suggested. [ABSTRACT FROM AUTHOR]

High power conversion efficiency (PCE) perovskite solar cells (PSCs) rely on optimal alignment of the energy bands between the perovskite absorber and the adjacent charge extraction layers. However, since most of the materials and devices of high performance are prepared by solution‐based techniques, a deposition of films with thicknesses of a few nanometers and therefore a detailed analysis of surface and interface properties remains difficult. To identify the respective photoactive interfaces, photoelectron spectroscopy measurements are performed on device stacks of methylammonium‐lead‐iodide (MAPI)‐based PSCs in classical and inverted architectures in the dark and under illumination at open‐circuit conditions. The analysis shows that vacuum‐deposited MAPI perovskite absorber layers are n‐type, independent of the architecture and of the charge transport layer that it is deposited on (n‐type SnO2 or p‐type NiOx). It is found that the majority of the photovoltage is formed at the n‐MAPI/p‐HEL (hole extraction layer) junction for both architectures, highlighting the importance of this interface for further improvement of the photovoltage and therefore also the PCE. Finally, an experimentally derived band diagram of the completed devices for the dark and the illuminated case is presented. [ABSTRACT FROM AUTHOR]

Wide‐bandgap perovskite solar cells (PSCs) with optimal bandgap (Eg) and high power conversion efficiency (PCE) are key to high‐performance perovskite‐based tandem photovoltaics. A 2D/3D perovskite heterostructure passivation is employed for double‐cation wide‐bandgap PSCs with engineered bandgap (1.65 eV ≤ Eg ≤ 1.85 eV), which results in improved stabilized PCEs and a strong enhancement in open‐circuit voltages of around 45 mV compared to reference devices for all investigated bandgaps. Making use of this strategy, semitransparent PSCs with engineered bandgap are developed, which show stabilized PCEs of up to 25.7% and 25.0% in four‐terminal perovskite/c‐Si and perovskite/CIGS tandem solar cells, respectively. Moreover, comparable tandem PCEs are observed for a broad range of perovskite bandgaps. For the first time, the robustness of the four‐terminal tandem configuration with respect to variations in the perovskite bandgap for two state‐of‐the‐art bottom solar cells is experimentally validated. [ABSTRACT FROM AUTHOR]

High‐efficiency perovskite‐based solar cells can be fabricated via either solution‐processing or vacuum‐based thin‐film deposition. However, both approaches limit the choice of materials and the accessible device architectures, due to solvent incompatibilities or possible layer damage by vacuum techniques. To overcome these limitations, the lamination of two independently processed half‐stacks of the perovskite solar cell is presented in this work. By laminating the two half‐stacks at an elevated temperature (≈90 °C) and pressure (≈50 MPa), the polycrystalline perovskite thin‐film recrystallizes and the perovskite/charge transport layer (CTL) interface forms an intimate electrical contact. The laminated perovskite solar cells with tin oxide and nickel oxide as CTLs exhibit power conversion efficiencies of up to 14.6%. Moreover, they demonstrate long‐term and high‐temperature stability at temperatures of up to 80 °C. This freedom of design is expected to access both novel device architectures and pairs of CTLs that remain usually inaccessible. [ABSTRACT FROM AUTHOR]

Perovskite absorber layers for thin-film solar cells can be fabricated by a variety of methods including solution- and vacuum-based methods. Solution-processed perovskite thin-films prepared by two-step methods often suffer from small grains and thus reduced optoelectronic performance. In this work, a simple and universal way to control the crystallization dynamics of perovskite (CH3NH3PbI3) layers prepared by thermal evaporation of lead iodide and a subsequent solution-based conversion in methylammonium iodide solution is presented. By adding small concentrations of the non-toxic additive hypophosphorous acid (HPA) in the second fabrication step, a facile way to maintain improved morphology and high quality perovskite films with large crystal size and low number of pin-holes is demonstrated. Therefore, this approach provides an additional handle to influence the structural properties of perovskite films. In this study, the improved morphology results in an overall increase in power conversion efficiency from 5.1% to 8.0%. The additive-assisted control of crystallization dynamics in perovskite layers is shown to be suitable both for small area deposition techniques, like spin-coating, as well as large scale deposition techniques, such as inkjet printing. Moreover, it is validated that the additive improves the crystallization on a large variety of substrate materials as well as in ambient and inert process environments. [ABSTRACT FROM AUTHOR]

Based on solution-processed kesterite-type Cu2ZnSn(S1- x,Se x)4 solar cells, a detailed investigation of the source and effects of sodium in the absorber will be presented. In contrast to most investigations in literature so far, the main process for sodium supply during selenization does not seem to be the diffusion out of the sodium-containing glass substrate but a transfer from the environment into the absorber. Studies on the influence of sodium on the morphological properties of the absorbers let us assume that the formation of big grains is not necessarily coupled to the presence of sodium during selenization. However, a beneficial effect on the electrical properties can mainly be seen in the open-circuit voltage ( Voc) and the fill factor (FF) which should be related to an increase in doping concentration ( NA). [ABSTRACT FROM AUTHOR]

Mater. i B 2021 b , I 31 i , 2104482 The originally published article contains an error in the calculation of the mean free path of methylammonium iodine (MAI) according to equation (2) in the main manuscript (wrong diameter for the MAI molecule), which also resulted in too low values for the mean free path of MAI in Figure 1b and a wrong explanation in the introductory part of the manuscript in section 2.1. Therefore, the conclusion that the loss in the effusive component of the MAI evaporation is due to the increased number of collisions between MAI molecules is unlikely. Most importantly, the influence of the substrate material (here polarity) on the film formation is not influenced by this initially wrong interpretation of our process since the substrate dependency is linked to the interaction of the substrate surface and the condensing molecules in this complex mixed process environment as shown throughout the manuscript. [Extracted from the article]

Transferring the high power conversion efficiencies (PCEs) of spin‐coated perovskite solar cells (PSCs) on the laboratory scale to large‐area photovoltaic modules requires a significant advance in scalable fabrication methods. Digital inkjet printing promises scalable, material, and cost‐efficient deposition of perovskite thin films on a wide range of substrates and in arbitrary shapes. In this work, high‐quality inkjet‐printed triple‐cation (methylammonium, formamidinium, and cesium) perovskite layers with exceptional thicknesses of >1 µm are demonstrated, enabling unprecedentedly high PCEs > 21% and stabilized power output efficiencies > 18% for inkjet‐printed PSCs. In‐depth characterization shows that the thick inkjet‐printed perovskite thin films deposited using the process developed herein exhibit a columnar crystal structure, free of horizontal grain boundaries, which extend over the entire thickness. A thin film thickness of around 1.5 µm is determined as optimal for PSC for this process. Up to this layer thickness X‐ray photoemission spectroscopy analysis confirms the expected stoichiometric perovskite composition at the surface and shows strong deviations and inhomogeneities for thicker thin films. The micrometer‐thick perovskite thin films exhibit remarkably long charge carrier lifetimes, highlighting their excellent optoelectronic characteristics. They are particularly promising for next‐generation inkjet‐printed perovskite solar cells, photodetectors, and X‐ray detectors. [ABSTRACT FROM AUTHOR]

Keywords: all-perovskite tandem solar cells; large grain; low-bandgap perovskites; solar cells; vacuum-assisted growth control This efficient low-bandgap perovskite solar cells enable achieving efficient all-perovskite tandem solar cells. All-perovskite tandem solar cells, large grain, low-bandgap perovskites, solar cells, vacuum-assisted growth control. [Extracted from the article]

A key challenge for the commercialization of perovskite photovoltaics is the transfer of high‐quality spin coated perovskite thin‐films toward applying industry‐scale thin‐film deposition techniques, such as slot‐die coating, spray coating, screen printing, or inkjet printing. Due to the complexity of the formation of polycrystalline perovskite thin‐films from the precursor solution, efficient strategies for process transfer require advancing the understanding of the involved dynamic processes. This work investigates the fundamental interrelation between the drying dynamics of the precursor solution thin‐film and the quality of the blade coated polycrystalline perovskite thin‐films. Precisely defined drying conditions are established using a temperature‐stabilized drying channel purged with a laminar flow of dry air. The dedicated channel is equipped with laser reflectometry at multiple probing positions, allowing for in situ monitoring of the perovskite solution thin‐film thickness during the drying process. Based on the drying dynamics as measured at varying drying parameters, namely at varying temperature and laminar air flow velocity, a quantitative model on the drying of perovskite thin‐films is derived. This model enables process transfer to industry‐scale deposition systems beyond brute force optimization. Via this approach, homogeneous and pinhole‐free blade coated perovskite thin‐films are fabricated, demonstrating high power conversion efficiencies of up to 19.5% (17.3% stabilized) in perovskite solar cells. [ABSTRACT FROM AUTHOR]

In this work, the authors realize stable and highly efficient wide‐bandgap perovskite solar cells that promise high power conversion efficiencies (PCE) and are likely to play a key role in next generation multi‐junction photovoltaics (PV). This work reports on wide‐bandgap (≈1.72 eV) perovskite solar cells exhibiting stable PCEs of up to 19.4% and a remarkably high open‐circuit voltage (VOC) of 1.31 V. The VOC‐to‐bandgap ratio is the highest reported for wide‐bandgap organic−inorganic hybrid perovskite solar cells and the VOC also exceeds 90% of the theoretical maximum, defined by the Shockley–Queisser limit. This advance is based on creating a hybrid 2D/3D perovskite heterostructure. By spin coating n‐butylammonium bromide on the double‐cation perovskite absorber layer, a thin 2D Ruddlesden–Popper perovskite layer of intermediate phases is formed, which mitigates nonradiative recombination in the perovskite absorber layer. As a result, VOC is enhanced by 80 mV. [ABSTRACT FROM AUTHOR]

High‐quality inorganic charge extraction layers are of key importance for efficient and stable perovskite‐based photovoltaics. In article number 1802995, Tobias Abzieher, Ulrich W. Paetzold, and co‐workers introduce oxygen‐assisted electron beam evaporation of NiOx as a promising approach for the fabrication of highly transparent hole transport layers. By integrating these layers in inkjet‐printed and all‐evaporated perovskite solar cells, record PCEs are achieved. [ABSTRACT FROM AUTHOR]

High‐quality charge carrier transport materials are of key importance for stable and efficient perovskite‐based photovoltaics. This work reports on electron‐beam‐evaporated nickel oxide (NiOx) layers, resulting in stable power conversion efficiencies (PCEs) of up to 18.5% when integrated into solar cells employing inkjet‐printed perovskite absorbers. By adding oxygen as a process gas and optimizing the layer thickness, transparent and efficient NiOx hole transport layers (HTLs) are fabricated, exhibiting an average absorptance of only 1%. The versatility of the material is demonstrated for different absorber compositions and deposition techniques. As another highlight of this work, all‐evaporated perovskite solar cells employing an inorganic NiOx HTL are presented, achieving stable PCEs of up to 15.4%. Along with good PCEs, devices with electron‐beam‐evaporated NiOx show improved stability under realistic operating conditions with negligible degradation after 40 h of maximum power point tracking at 75 °C. Additionally, a strong improvement in device stability under ultraviolet radiation is found if compared to conventional perovskite solar cell architectures employing other metal oxide charge transport layers (e.g., titanium dioxide). Finally, an all‐evaporated perovskite solar mini‐module with a NiOx HTL is presented, reaching a PCE of 12.4% on an active device area of 2.3 cm2. A highly transparent nickel oxide hole transport layer prepared by oxygen‐assisted electron beam evaporation for perovskite‐based photovoltaics is reported. Using these layers in perovskite solar cells, efficient devices with stable power conversion efficiencies up to 18.5% for inkjet‐printed absorbers and 15.4% for co‐evaporated absorbers are demonstrated. In addition, good stability at elevated temperature and under ultraviolet radiation is shown. [ABSTRACT FROM AUTHOR]