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Surface textures are indispensable to minimize optical losses in perovskite-based solar cells. However, the solution-processing of perovskite layers is often not compatible with textured substrates, and little is known about the film growth thereon. This study aims to elucidate the growth process of perovskite layers from solution on textured substrates and to identify the texture features ensuring compatibility with perovskite solution-processing. Using nanoimprint-lithography we prepared three different periodically as well as randomly textured glass substrates for spin-coated perovskite solar cells, of which one was duplicated from a commercially available texture. During the perovskite crystallization process, a time-resolved in situ photoluminescence measurement was conducted. The photoluminescence signal was not found to substantially alter using textured substrates with texture heights around 500 nm. Optical absorptance spectroscopy and scanning electron microscopic imaging were applied to investigate the growth, crystal structure, and optical properties of solution-processed perovskite on top of different textures. We find that periodic textures with height around 500 nm enable homogeneous solution-processed perovskite layers with optimized optical performance. In contrast, texture heights of several micrometers lead to macroscopic holes in the perovskite film. The results of this study will help to find optimum optical textures for high-efficiency perovskite single-junction and perovskite-silicon tandem solar cells.

This study explores the influence of temperature–time conditions, surfactants, and varied waste compositions on the curing of geopolymer gels, a foam formation with the properties of porous geopolymers. Findings reveal that a 6 h curing period leads to a density of 435 kg/m3 and strength of 0.66 MPa, with notable improvements at 12 h. Comparing 12 to 24 h curing, differences in characteristics remain within 5%, highlighting the 12 h period as more energy-efficient. Sodium stearate-based samples exhibit excellent properties, significantly boosting strength while maintaining overall properties. Microwave curing achieves the lowest density (291 kg/m3) and closely parallels properties of samples cured conventionally for 12 h. However, it leads to complete destruction in sodium stearate-modified gels due to the Dumas reaction, making it unsuitable above 200 °C. Optimal properties emerge from compositions using sodium stearate and oven curing, achieving densities of 334 kg/m3 and strengths of 1.08 MPa (Severodvinsk CHPP-1) and 373 kg/m3 and 1.17 MPa (Novocherkassk SDPP). Although microwave curing allows for high energy efficiency, its high temperature demands necessitate careful material selection. This study offers insight into enhancing geopolymer properties while emphasizing the importance of tailored curing methods for sustainable material development. [ABSTRACT FROM AUTHOR]

In modern photovoltaic (PV) systems such as bifacial and building‐integrated PV, a big share of sunlight impinges at large incident angles on the air‐to‐glass module interface. These designs exceedingly call for effective omnidirectional antireflective (AR) measures. Texturing of PV cover glasses can effectively mitigate reflection losses in a broad spectral and angular range. Numerous individual textures have been presented in the literature; however, the lack of consistent material stacks hinders a comparative evaluation. Herein, UV‐nanoimprint lithography is used to fabricate and analyze 12 different artificial and bioreplicated textures from nano‐ to mesoscale on glass. The angle‐resolved reflectance is examined for incident angles from 5° to 80° and analyzed the scattering properties. For example, the effect of the investigated textures on the annual energy yield is calculated for a tilted bifacial PV module located in Berlin, Germany. While well‐known moth‐eye nanostructures exhibit excellent AR behavior near‐normal incidence, their shallow angle performance is often not reported. The best‐performing textures exhibit features on microscale and a large surface enhancement factor, increasing the annual energy yield up to 5% when compared to nontextured devices. The results give clear design guidelines for textured glasses of future PV applications. [ABSTRACT FROM AUTHOR]

Nb2O5 shows promising features for electron transport layers (ETL) in perovskite solar cells (PSCs), such as suitable band alignment and ultraviolet stability. Here, we studied the incorporation of Ti3C2Tx MXene in a solution-processable compact layer as a component of ETLs for PSCs. The addition of 0.4 wt% MXene with respect to niobium ethoxide was shown to enhance the PCE (19.46% for the champion device) and stability (96% of its original PCE after 500 hours) compared to pristine devices. The improved performance of the Nb2O5–Ti3C2 devices (0.4 wt%) could be attributed to the adapted alignment of the energy band between perovskite and ETL layers, which favors electron transport and extraction. In addition, the high electrical conductivity of MXenes worked as a free pathway for the extracted electrons preventing charge recombination. These features were corroborated by Photo-CELIV, which showed a higher density of extracted charges and increased charge carrier lifetime for Nb2O5–Ti3C2 based devices. Hence, the results unveiled in this work indicate that MXenes are promising 2D materials for tuning Nb2O5 based ETLs. Future works shall focus on other MXene compounds to further boost PSC performance and stability. [ABSTRACT FROM AUTHOR]

The regularities of obtaining foamed alkali-activated geopolymer materials based on different wastes of coal power engineering (fly ash, fuel (boiler) slag, ash, and slag mixture) were considered. The phase composition of the studied waste showed the presence of a significant amount of the amorphous phase, as well as a crystalline phase. mostly in the form of high quartz. The microstructure of studied the waste showed that the fly ash consisted of monodisperse hollow aluminosilicate microspheres, the fuel slag was represented by polydisperse irregular particles, and the ash and slag mixture included both of these materials in different ratios. Blowing agents such as aluminum powder, hydrogen peroxide, and sodium hypochlorite were chosen to achieve the porous structure of the geopolymer materials. The calculations of the geopolymer precursor compositions were carried out. Samples were synthesized, and their physical and mechanical properties, such as density, strength, porosity, and thermal conductivity, were analyzed. The micro- and macrostructure of the samples, as well as the pore distribution of the obtained geopolymers were studied. Conclusions were made on the choice of the most-optimal foaming agent and the optimal coal combustion waste suitable for the synthesis of the geopolymer materials. [ABSTRACT FROM AUTHOR]

The effect of formation of a periodic surface microrelief upon tension of polymeric substrates with thin hard coatings under specified conditions (the processing temperature below the glassing temperature, elongation up to 250%, elongation rate <5 mm/min) is described. The microrelief period ranges from 0.5 μm up to hundreds of micrometers, its height up to 1 μm. Methods are proposed to measure low values of the optical path length in media Δn∼λ and azimuthal anchoring energy of a liquid crystal on microreliefed surfaces. [ABSTRACT FROM AUTHOR]

Stability issues could prevent lead halide perovskite solar cells (PSCs) from commercialization despite it having a comparable power conversion efficiency (PCE) to silicon solar cells. Overcoming drawbacks affecting their long-term stability is gaining incremental importance. Excess lead iodide (PbI 2 ) causes perovskite degradation, although it aids in crystal growth and defect passivation. Herein, we synthesized functionalized oxo-graphene nanosheets (Dec-oxoG NSs) to effectively manage the excess PbI 2 . Dec-oxoG NSs provide anchoring sites to bind the excess PbI 2 and passivate perovskite grain boundaries, thereby reducing charge recombination loss and significantly boosting the extraction of free electrons. The inclusion of Dec-oxoG NSs leads to a PCE of 23.7 % in inverted (p-i-n) PSCs. The devices retain 93.8 % of their initial efficiency after 1,000 hours of tracking at maximum power points under continuous one-sun illumination and exhibit high stability under thermal and ambient conditions., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)