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Abstract Organic–inorganic hybrid perovskite is the most promising active layer for new generation of solar cells. Despite of highly efficient perovskite active layer conventionally fabricated by spin coating methods, the need for using toxic solvents like dimethylformamide (DMF) required for dissolving low soluble metal precursors as well as the difficulties for upscaling the process have restricted their practical development. To deal with these shortcomings, in this work, lead sulphide as the lead metal precursor was produced by aqueous chemical bath deposition. Subsequently, PbS films were chemically converted to PbI2 and finally to mixed-cation mixed halide perovskite films. The microstructural, optical and solar cell performance of mixed cation mixed halide perovskite films were examined. Results show that controlling the morphology of PbI2 platelets achieved from PbS precursor films enabled efficient conversion to final perovskite films. Using this processing technique, smooth and pin hole-free perovskite films having columnar grains of about 800 nm and a bandgap of 1.55 eV were produced. The solar cell performance consisting of such perovskite layers gave rise to a notable power conversion efficiency of 11.35% under standard solar conditions. The proposed processing technique is very promising towards an environmentally friendly method for the production of large-scale high efficient perovskite solar cells.

Germanium (Ge) has potential as a dopant suitable for the hematite-based photoelectrochemical water splitting system. Here, the authors report the fabrication of Ge doped porous hematite and demonstrate an efficient tandem system of Ge doped porous hematite and the perovskite solar cell.

Abstract Although antimony selenoiodide (SbSeI) exhibits a suitable bandgap as well as interesting physicochemical properties, it has not been applied to solar cells. Here the fabrication of SbSeI solar cells is reported for the first time using multiple spin‐coating cycles of SbI3 solutions on Sb2Se3 thin layer, which is formed by thermal decomposition after depositing a single‐source precursor solution. The performance exhibits a short‐circuit current density of 14.8 mA cm−2, an open‐circuit voltage of 473.0 mV, and a fill factor of 58.7%, yielding a power conversion efficiency (PCE) of 4.1% under standard air mass 1.5 global (AM 1.5 G, 100 mW cm−2). The cells retain ≈90.0% of the initial PCE even after illuminating under AM 1.5G (100 mW cm−2) for 2321 min. Here, a new approach is provided for combining selenide and iodide as anions, to fabricate highly efficient, highly stable, green, and low‐cost solar cells.

Abstract Strain induced by lattice distortion is one of the key factors that affect the photovoltaic performance via increasing defect densities. The unsatisfied power conversion efficiencies (PCEs) of solar cells based on antimony chalcogenides (Sb‐Chs) are owing to their photoexcited carriers being self‐trapped by the distortion of Sb2S3 lattice. However, strain behavior in Sb‐Chs‐based solar cells has not been investigated. Here, strain tuning in Sb‐Chs is demonstrated by simultaneously replacing Sb and S with larger Bi and I ions, respectively. Bi/I codoped Sb2S3 cells are fabricated using poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b']dithiophene)‐alt‐4,7‐(2,1,3‐enzothiadiazole)] as the hole‐transporting layer. Codoping reduced the bandgap and rendered a bigger tension strain (1.76 × 10−4) to a relatively smaller compression strain (−1.29 × 10−4). The 2.5 mol% BiI3 doped Sb2S3 cell presented lower trap state energy level than the Sb2S3 cell; moreover, this doping amount effectively passivated the trap states. This codoping shows a similar trend even in the low bandgap Sb2(SxSe1‐x)3 cell, resulting in 7.05% PCE under the standard illumination conditions (100 mW cm−2), which is one of the top efficiencies in solution processing Sb2(SxSe1‐x)3 solar cells. Furthermore, the doped cells present higher humidity, thermal and photo stability. This study provides a new strategy for stable Pb‐free solar cells.

Abstract Many organic cations in halide perovskites have been studied for their application in perovskite solar cells (PSCs). Most organic cations in PSCs are based on the protic nitrogen cores, which are susceptible to deprotonation. Here, a new candidate of fully alkylated sulfonium cation (butyldimethylsulfonium; BDMS) is designed and successfully assembled into PSCs with the aim of increasing humidity stability. The BDMS‐based perovskites retain the structural and optical features of pristine perovskite, which results in the comparable photovoltaic performance. However, the fully alkylated aprotic nature of BDMS shows a much more pronounced effect on the increase in humidity stability, which emphasizes a generic electronic difference between protic ammonium and aprotic sulfonium cation. The current results would pave a new way to explore cations for the development of promising PSCs.

Excess lead iodide in the mixed halide perovskites solar cells leads to high device performance but its origin remains elusive. Here Park et al. unveil the underlying microscopic mechanism to be promoting the oriented growth of the perovskites crystals and reducing the defect concentration.

Bandgap-engineered monodisperse HgTe NCs of different sizes were synthesized by means of a facile temperature-control method, a non-aqueous and non-Te-gas process. The photo-physical properties of the synthesized NCs in a simple photovoltaic device were tested. It was shown that this cell is capable of processing signals up to the 100 kHz level below 3 dB and hence is suitable for use in NIR photodetection. [ABSTRACT FROM AUTHOR]

Er-doped Al2O3–SiO2 (1/9 in mol ratio of Al2O3/SiO2) thin films were prepared by using a modified sol–gel process. The modified process entails the precipitation and digestion of Er(OH)3, obtained from the reaction between Er ions and NH4OH in solution. Thin films were deposited on Si wafers by using a spin coating technique (3000 rpm) and the coated films were heat treated at different temperatures for 1 h in an oxygen-purged furnace. All the films were structurally characterized by the X-ray diffraction technique using Cu Kα radiation. Refractive indices and the morphologies of the films were studied using a spectroscopic phase modulated ellipsometer and atomic force microscopy, respectively. It was observed that the films were crack free and of about 0.4 μm thickness in a single spin coating and both the lifetime and the photoluminescence intensity of Er ions increased with increasing the annealing temperature. The luminescence properties of the Er-doped Al2O3–SiO2 made by a conventional and our modified doping process were compared and discussed from the stand point of peak intensities and lifetimes as a function of annealing temperatures. It is to be noted here that our modified process was found to be more effective in reducing the clustering of Er ions in Al2O3–SiO2 materials as compared to that of the conventional method. [ABSTRACT FROM AUTHOR]

Studies the formation of crystaline titanium dioxide sols from a titanium peroxide solution using photoluminescence spectroscopy and describes the interfacial interaction between the sol and water, revealed by the decay of luminescence for a collodial dispersion in an aqueous solution. Details of experimental procedure.

A PbS-sensitized photovoltaic photodetector responsive to near-infrared (NIR) light was fabricated by depositing monolayered PbS nanoparticles on a mesoporous TiO2 (mp-TiO2) film via the spin-assisted successive ionic layer adsorption and reaction (SILAR) method. By adjusting the size and morphology of the PbS nanoparticles through repeated spin-assisted SILAR cycles, the PbS-sensitized photovoltaic photodetector achieved an external quantum efficiency of 9.3% at 1140 nm wavelength and could process signals up to 1 kHz. [ABSTRACT FROM AUTHOR]

A convenient solvothermal single-source route has been developed for the bulk synthesis of CdS nanorods using new air stable dimeric cadmium(II) complex of S-benzyldithiocarbazate, [Cd(PhCH2SC(=S)NHNH2)Cl2]2, at a relatively low temperature. The decomposition of the precursor was made by heating at 160°C in hexamethylenediamine (HMDA) to give amine capped CdS nanocrystals having yield ca. 90%; nano-dimensional rods are clearly visible in transmission electron microscope (TEM). The nanorods have been further characterized by X-ray diffraction (XRD), energy dispersed X-ray spectroscopy (EDX), FTIR and optical measurements. The structure of precursor was also established by single crystal X-ray crystallography. [Copyright &y& Elsevier]

The band gap of formamidinium lead iodide (FAPbI3) perovskites allows broader absorption of the solar spectrum relative to conventional methylammonium lead iodide (MAPbI3). Because the optoelectronic properties of perovskite films are closely related to film quality, deposition of dense and uniform films is crucial for fabricating high-performance perovskite solar cells (PSCs). We report an approach for depositing high-quality FAPbI3 films, involving FAPbI3 crystallization by the direct intramolecular exchange of dimethylsulfoxide (DMSO) molecules intercalated in PbI2 with formamidinium iodide. This process produces FAPbI3 films with (111)-preferred crystallographic orientation, large-grained dense microstructures, and flat surfaces without residual PbI2. Using films prepared by this technique, we fabricated FAPbI3-based PSCs with maximum power conversion efficiency greater than 20%. [ABSTRACT FROM AUTHOR]