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Inorganic CsPbI3 perovskite solar cells (CsPbI3 PSCs) have attracted extensive attention because of their excellent thermal stability and appropriate bandgap for tandem solar cells. At present, intermediate phase engineering with organic additive, e.g., dimethyl amine iodide (DMAI), is the most common method to obtain high‐efficiency CsPbI3 PSCs. However, it remains controversial whether the intermediate phase is entirely converted into a pure CsPbI3 phase. By exploring the effect of annealing temperature, herein, it is demonstrated that substantial organic residues remain in the produced films while using the current standard recipes of DMA+‐assisted synthesis of Cs1−xDMAxPbI3 perovskites. Thermal gravimetric and nuclear magnetic resonance show that DMA+ remains in films annealed at a standard annealing temperature of 190 °C. The DMA+ does, however, disappear if the annealing temperature is increased to 340 °C, which leads to a larger grain size, a contraction of the lattice, a narrower bandgap, and a redshift of the absorption onset. Though both Cs1−xDMAxPbI3 and CsPbI3 perovskite solar cells show decent efficiencies, the pure CsPbI3 perovskite solar cells annealed at a higher temperature demonstrate higher operational stability. [ABSTRACT FROM AUTHOR]

Antimony sulfide is an emerging 1D nontoxic Earth‐abundant photovoltaic material with favorable wide bandgap as a suitable top‐cell candidate for multijunction tandem solar cells. However, the current fabrication technology for Sb2S3 solar cells relies heavily on a high‐purity Sb2S3 source, which limits its large‐scale deployment. Therefore, it is attractive to fabricate the Sb2S3 solar cells directly from the raw stibnite source, which can be cost effective by avoiding the complicated, costly purification and refinement process of the stibnite ore, while reducing process‐emitted pollution. Herein, high‐quality Sb2S3 films (thickness: ≈1 μm) by the vapor transport deposition of raw stibnite ore powder are obtained, followed by a sulfurization process to remove the surface oxides and facilitate alkali element redistribution. In this way, the particle size is increased from ≈500 nm to ≈1.5 μm, the carrier concentration of the Sb2S3 film is increased from ≈1015 to ≈1016 cm−3, and the power conversion efficiency of Sb2S3 solar cell is increased by more than two times. Through the elemental distribution analysis, it is found that it is the redistribution of alkali elements introduced from the natural stibnite ore that induces the grain growth, contributes toward defect suppression, and leads toward enhanced device performance. [ABSTRACT FROM AUTHOR]

Bismuth triiodide (BiI3) is a particularly promising absorber material for inorganic thin-film solar cells due to its merits of nontoxicity and low cost. However, one key factor that limits the efficiency of BiI3 solar cells is the film morphology, which is strongly correlated with the trap states of the BiI3 film. Herein, we report a coordination engineering strategy by using Lewis base dimethyl sulfoxide (DMSO) to induce the formation of a stable BiI3(DMSO)2 complex for controlling the morphology of BiI3 films. Density functional theory calculations further provide a theoretical framework for understanding the interaction of the BiI3(DMSO)2 complex with BiI3. The obtained BiI3(DMSO)2 complex could assist the fabrication of highly uniform and pinhole-free films with preferred crystallographic orientation. This high-quality film enables reduced trap densities, a suppressed charge recombination, and improved carrier mobility. In addition, the use of copper(I) thiocyanate (CuSCN) as a hole transport layer improves the charge transport, enabling the realization of solar cells with a record power conversion efficiency of 1.80% and a champion fill factor of 51.5%. Our work deepens the insights into controlling the morphology of BiI3 thin films through the coordination engineering strategy and paves the way toward further improving the photovoltaic performances of BiI3 solar cells.

Recently, Cu 2 BaSnS 4 (CBTS) has emerged as a leading candidate to improve cationic ordering, which limits performance of solar cells, in Cu 2 ZnSnS 4 (CZTS) absorber layers. While non-toxic solution based approaches appear very attractive for the deposition of the CBTS layers, the formation of secondary phases stemming from poor control of composition must be suppressed. While preparing CBTS thin films from 2-methoxy ethanol based molecular solutions, we find critical dependence of phase evolution on the Ba concentration in the solution. From the systematic variation in molar concentration of cations and sulfurization parameters we have established the favourable reaction pathway leading to the formation of the single phase CBTS via intermediate solid-state binary and tertiary compounds. The resultant films exhibited significantly reduced effects of cation antisite disorder compared to CZTS as reflected from a symmetric room temperature photoluminescence peak. The films had a band gap of ∼2.0 eV and showed considerable white light sensitivity. Detailed electrical and electro-impedance measurements were carried out that revealed p-type conductivity with a carrier concentration of 1.7×1014 cm−3. [Display omitted] • Reaction pathway for growth of phase pure CBTS films in a molecular solution method is established. • Influence of molar concentration of reagent solutions and the sulfurization ambience on properties of films has been examined. • A symmetric PL peak suggested reduced cation disorder in the films. • Electro-impedance measurements showed p-type conductivity with carrier density of ∼1014/cm3. [ABSTRACT FROM AUTHOR]

Solar cells are prepared combining ZnO as n-type window In2S3 as buffer layer and CuInS2 as p-type absorbing layer. Superstrate configuration is chosen so that all the materials could be prepared using inexpensive and eco-friendly techniques, based on solution processed deposition methods and non-toxic materials, avoiding vacuum high temperature Cd-containing layers and KCN purification stages. Also, no further sulfurization treatment is involved in the preparation. To improve the collection efficiency, the cells are built using two different ZnO nanostructures (with and without Cl-doping) and compared to the response of a cell prepared with just one dense ZnO layer. The photoresponse of the three different solar cells is analysed by J-V curves under illumination and intensity-modulated photovoltage/photocurrent spectroscopy. A systematic characterization of the morphology and composition is carried out using X-ray diffraction Raman confocal and electronic microscopy. The introduction of a nanostructured layer is not enough to produce a marked improvement in any of the electrical parameters. Instead, the presence of Cl-doped nanopillars is shown to increase the efficiency of the solar cells up to a maximum value of 2.8%. A better series resistance together with a higher value for the charge collection efficiency contributes to explain the corresponding improvement in cell efficiency. [ABSTRACT FROM AUTHOR]

This study outlines the synthesis and physicochemical characteristics of a solution-processable iron manganite (FeMnO 3 ) nanoparticles via a chemical combustion method using tartaric acid as a fuel whilst demonstrating the performance of this material as a n-type photoactive layer in all-oxide solar cells. It is shown that the solution combustion synthesis (SCS) method enables the formation of pure crystal phase FeMnO 3 with controllable particle size. XRD pattern and morphology images from TEM confirm the purity of FeMnO 3 phase and the relatively small crystallite size (∼13 nm), firstly reported in the literature. Moreover, to assemble a network of connected FeMnO 3 nanoparticles, β -alanine was used as a capping agent and dimethylformamide (DMF) as a polar aprotic solvent for the colloidal dispersion of FeMnO 3 NPs. This procedure yields a ∼500 nm thick FeMnO 3 n-type photoactive layer. The proposed method is crucial to obtain functional solution processed NiO/FeMnO 3 heterojunction inorganic photovoltaics. Photovoltaic performance and solar cell device limitations of the NiO/FeMnO 3 -based heterojunction solar cells are presented., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Papadas, Ioakeimidis, Vamvasakis, Eleftheriou, Armatas and Choulis.)

Antimony selenide (Sb 2 Se 3) is a p-type semiconductor, considered as an excellent photovoltaic absorber for its high absorption coefficient in the visible region and a nearly optimal band-gap for single-junction solar cells. The simple binary composition, together with non-toxic and earth-abundant constituents make this material very promising toward industrial production of low-cost thin-film solar cells. Theoretical calculations and experimental data have confirmed that Sb 2 Se 3 exhibits strong anisotropic optoelectronic properties, due to the presence of infinite covalent (Sb 4 Se 6) n ribbons along the (001) direction, whereas weak van der Waals interactions occur between ribbons. In such anisotropic materials, electronic transport is strongly affected by crystal structure: when ribbons are aligned perpendicularly to the solar cell surface, a better collection of photogenerated current occurs, leading to larger photovoltaic conversion efficiencies. In order to understand the alignment mechanisms of ribbons, Sb 2 Se 3 thin films were grown by Low-Temperature Pulsed Electron Deposition (LT-PED) technique at different temperatures (from 200 °C to 400 °C) on a variety of substrates, such as glass, molybdenum, CdS, Fluorine-doped Tin Oxide (FTO) and nanostructured ZnO. The structural and morphological characterization of the Sb 2 Se 3 films, performed by out-of-plane and in-plane X-Ray Diffraction and micro-Raman spectroscopy, demonstrated that ribbon alignment along the surface normal is strongly dependent on the used substrate. The comparison between solar cells grown in substrate configuration on Mo and FTO, clearly demonstrates the influence of ribbon orientation on short-circuit current. Image 1 • Pulsed Electron Deposition allows fast deposition of stoichiometric Sb 2 Se 3. • No high temperature annealing nor selenization in toxic gas are needed for Sb 2 Se 3. • Sb2Se3 can be used as absorber layer for bifacial solar cells grown on FTO. • Molybdenum promotes high crystalline quality Sb2Se3 with (020) orientation. • Sb2Se3 Ribbon orientation greatly affect the charge collection of the devices. [ABSTRACT FROM AUTHOR]

• Thin Au, Au-NP, Ag-NP and AgO bi-layer and tri-layer ITO-based films were studied. • Strong absorption peaks were detected for Ag-NP and Au-NP colloidal solutions. • A maximum transmittance of 91.5% was attained for (AgO)I and (I(AgO)I) thin films. • A band gap energy of 3.75 eV was estimated for (AgO)I and (I(AgO)I) thin films. • An improvement in power conversion efficiency (PCE) from 3.8 to 4.9% was achieved. In this investigation, ITO-based bi-layer and tri-layer thin film coatings (~130 nm) were synthesized via a sol-gel spin-coating process and annealed at 500 °C. Thin layers of Au, Au-NPs, Ag-NPs and AgO were inserted underneath ITO films to form bi-layer thin film systems and/or encapsulated between two thin ITO layers to form tri-layer thin film systems. The effects of incorporating these layers with ITO thin films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), UV–Vis spectroscopy, four-point probes and Hall effect. XRD results confirmed the presence of a body-centred cubic structure of indium oxide for all synthesized ITO-based coatings with an average grain size ~30 nm. FESEM images of all fabricated films revealed the formation of dense surfaces with grain-like morphologies confirming the formation of a polycrystalline structure of ITO. Optical studies on the Ag-NPs and Au-NPs colloidal solutions resulted in absorption peaks featured at wavelengths 405 and 531 nm, indicating the formation of 10–14 nm and 48 nm Ag and Au nanoparticles, respectively. The highest optical transparency and band gap energy were found to be ~91.5% and 3.75 eV for (AgO)I and (I(AgO)I) thin films, respectively. The lowest electrical resistivity of 1.2 × 10−4 Ω·cm, along with the highest carrier concentration of 11.4 × 1020 cm−3 and mobility 40 cm2/V.s were obtained from the IAuI thin film. An improvement in the power conversion efficiency (PCE) from 3.8 to 4.9% was achieved in an organic solar cell by replacing the conventional pure ITO electrode with the (I(AgO)I) electrode. [ABSTRACT FROM AUTHOR]

All-inorganic CsPbIBr 2 perovskite has recently received growing attention due to its balanced band gap and excellent environmental stability. However, the requirement of high-temperature processing limits its application in flexible devices. Herein, a low-temperature seed-assisted growth (SAG) method for high-quality CsPbIBr 2 perovskite films through reducing the crystallization temperature by introducing methylammonium halides (MAX, X = I, Br, Cl) is demonstrated. The mechanism is attributed to MA cation based perovskite seeds, which act as nuclei lowering the formation energy of CsPbIBr 2 during the annealing treatment. It is found that methylammonium bromide treated perovskite (Pvsk-Br) film fabricated at low temperature (150 °C) shows micrometer-sized grains and superior charge dynamic properties, delivering a device with an efficiency of 10.47%. Furthermore, an efficiency of 11.1% is achieved for a device based on high-temperature (250 °C) processed Pvsk-Br film via the SAG method, which presents the highest reported efficiency for inorganic CsPbIBr 2 solar cells thus far., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)