Expression of Concern: Concordantly fabricated heterojunction ZnO-TiO2 nanocomposite electrodes via a co-precipitation method for efficient stable quasi-solid-state dye-sensitized solar cells.

Expression of concern for 'Concordantly fabricated heterojunction ZnO-TiO2 nanocomposite electrodes via a co-precipitation method for efficient stable quasi-solid-state dye-sensitized solar cells' by Ahmed Esmail Shalan et al., RSC Adv., 2015, 5, 103095-103104, DOI: 10.1039/C5RA21822E.

Synthesis and numerical simulation of formamidinium-based perovskite solar cells: a predictable device performance at NIS-Egypt.

Formamidinium lead triiodide (δ-FAPbI3)-based perovskite solar cells showed remarkable potential as light harvesters for thin-film photovoltaics. Herein, the mechanochemical synthesis of δ-FAPbI3, MAPbI3, and mixed-cation FA1-xMAxPbI3 with (x = 0.3, 0.5, and 0.7) perovskite materials were prepared as a novel green chemistry method for scaling up production. Crystallinity, phase identification, thermal stability, optoelectronic properties, and nanoscale composition are discussed. The results demonstrated that the prepared mixed-cation samples are enhanced in the visible absorption region and are consistent with previous works. The crystal structure of δ-FAPbI3 was altered to a cubic structure due to the change in FA-cation. Moreover, the performance of [Formula: see text]-FA-based perovskites was investigated using the Solar Cell Capacitance Simulator (SCAPS-1D) software. The validity of the device simulation was confirmed by comparing it to real-world devices. The photovoltaic characteristics and impact of absorber thickness on device performance were explained. The [Formula: see text]-FA-based solar cell with a 50% MA-doped molar ratio shows a better performance with an efficiency of 26.22% compared to 8.43% for δ-FAPbI3. The outcome results of this work confirm the beneficial effect of mixed cations on device operation and advance our knowledge of the numerical optimization of perovskite-based solar cells.

Correction: Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation.

[This corrects the article DOI: 10.1039/D3RA00805C.].

AgSCN as a new hole transporting material for inverted perovskite solar cells.

A novel HTM based on silver thiocyanate (AgSCN) was designed to be useable in p-i-n perovskite solar cells (PSCs). With mass yield, the AgSCN was synthesized in the lab and elucidated by XRD, XPS, Raman spectroscopy, UPS, and TGA. The production of thin, highly conformal AgSCN films that allow for quick carrier extraction and the collection was made possible by a fast solvent removal approach. Photoluminescence experiments have shown that adding AgSCN has improved the ability to transfer charges between HTL and perovskite layer compared to PEDOT:PSS at the interface. Crystallographic discrepancies in the polycrystalline perovskite film are discovered upon further examination of the film's microstructure and morphology, pointing to the development of templated perovskite on the surface of AgSCN. In comparison to devices due to the well-known PEDOT:PSS, the open circuit voltage (VOC) is increased by AgSCN with its high work function by 0.1-1.14 V (1.04 V for PEDOT:PSS). With a power conversion efficiency (PCE) of 16.66%, a high-performance PSCs are effectively generated using CH3NH3PbI3 perovskite compared to 15.11% for controlled PEDOT:PSS devices. The solution-processed inorganic HTL was demonstrated employing straightforward in order to build durable and effective flexible p-i-n PSCs modules or their use as a front cell in hybrid tandem solar cells.

Controlling barrier height and spectral responsivity of p-i-n based GeSn photodetectors via arsenic incorporation.

GeSn compounds have made many interesting contributions in photodetectors (PDs) over the last ten years, as they have a detection limit in the NIR and mid-IR region. Sn incorporation in Ge alters the cut off wavelength. In the present article, p-i-n structures based on GeSn junctions were fabricated to serve as PDs. Arsine (As) is incorporated to develop n-GeSn compounds via a metal induced crystallization (MIC) process followed by i-GeSn on p-Si wafers. The impact of As and Sn doping on the strain characteristics of GeSn has been studied with high resolution transmission electron microscopy (HRTEM), X-ray diffraction and Raman spectroscopy analyses. The direct transitions and tuning of their band energies have been investigated using diffuse reflectance UV-vis spectroscopy and photoluminescence (PL). The barrier height and spectral responsivity have been controlled with incorporation of As. Variation of As incorporation into GeSn Compounds shifted the Raman peak and hence affected the strain in the Ge network. UV-vis spectroscopy showed that the direct transition energies are lowered as the Ge-As bonding increases as illustrated in Raman spectroscopy investigations. PL and UV-vis spectroscopy of annealed heterostructures at 500 °C showed that there are many transition peaks from the UV to the NIR region as result of oxygen vacancies in the Ge network. The calculated diode parameters showed that As incorporation leads to an increase of the height barrier and thus dark current. Spectral response measurements show that the prepared heterojunctions have spectral responses in near UV and NIR regions that gives them opportunities in UV and NIR photodetection-applications.

Promising Nitrogen-Doped Graphene Derivatives; A Case Study for Preparations, Fabrication Mechanisms, and Applications in Perovskite Solar Cells.

Graphene (G) has been a game-changer for conductive optical devices and has shown promising aspects for its implementation in the power industry due to its diverse structures. Graphene has played an essential role as electrodes, hole transport layers (HTLs), electron transport layers (ETLs), and a chemical modulator for perovskite layers in perovskite solar cells (PSCs) over the past decade. Nitrogen-doped graphene (N-DG) derivatives are frequently evaluated among the existing derivatives of graphene because of their versatility of design, easy synthesis process, and high throughput. This review presents a state-of-the-art overview of N-DG preparation methods, including wet chemical process, bombardment, and high thermal treatment methods. Furthermore, it focuses on different structures of N-DG derivatives and their various applications in PSC applications. Finally, the challenges and opportunities for N-DG derivatives for the continuous performance improvement of PSCs have been highlighted.

Magnetic TiO2/CoFe2O4 Photocatalysts for Degradation of Organic Dyes and Pharmaceuticals without Oxidants.

In the current study, CoFe2O4 and TiO2 nanoparticles were primarily made using the sol-gel method, and subsequently, the hybrid magnetic composites of TiO2 loaded with CoFe2O4 (5-15 percent w/w) were made using a hydrothermal procedure. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) were all used to thoroughly characterize the materials. Additionally, the zero-charge point (ZCP) determination, the examination of the pore structure by nitrogen adsorption, and an evaluation of magnetic properties were performed. Six organic dye pollutants were selected to evaluate the performance of the synthesized nanocomposites toward photocatalytic degradation, including methylene blue (MB), methyl orange (MO), crystal violet (CV), acridine orange (AO), rhodamine B (RhB), and rhodamine 6G (R-6G). Photodegradation of tetracycline (TL), a model pharmaceutical pollutant, was also studied under UV and visible light. The composites exhibited a high degradation performance in all cases without using any oxidants. The photocatalytic degradation of tetracycline revealed that the CoFe2O4/TiO2 (5% w/w) composite exhibited a higher photocatalytic activity than either pure TiO2 or CoFe2O4, and thus attained 75.31% and 50.4% degradation efficiency under UV and visible light, respectively. Trapping experiments were conducted to investigate the photodegradation mechanism, which revealed that holes and super oxide radicals were the most active species in the photodegradation process. Finally, due to the inherent magnetic attributes of the composites, their easy removal from the treated solution via a simple magnet became possible.

Self-doping synthesis of trivalent Ni2O3 as a hole transport layer for high fill factor and efficient inverted perovskite solar cells.

Nickel oxide (NiOx) as a hole transport layer has been vastly investigated in perovskite solar cells (PSCs) due to the nature of p-type doping, highly transparent materials, and deep-lying valence bands. In this paper, a new phase based on trivalent Ni2O3 is synthesized by low temperature solution processing of mixed nickel (acetate/nitrate). In comparison, high-temperature solution-processing of divalent NiOx resulted in novel Ni2O3 thin films that display better consistency and superior energy compatibility with perovskite thin films. In this respect, high-performance perovskite solar cells are efficiently produced utilizing MA0.85FA0.15PbI0.9Cl0.1 perovskite with a power conversion efficiency (PCE) reaching 17.89% and negligible hysteresis comparable to 14.37% for NiOx. The Ni2O3-based PSCs reported the highest fill factor (FF) (82.66%) compared to that of divalent NiOx (67.53%). Different characterization studies and analyses supply proof of improved film quality, increased transport and extraction of charges, and suppressed charge recombination. Meanwhile, the device exhibits low hysteresis compared to sol-gel-processed NiOx.

Coordinated Optical Matching of a Texture Interface Made from Demixing Blended Polymers for High-Performance Inverted Perovskite Solar Cells.

The continuing increase of the efficiency of perovskite solar cells has pushed the internal quantum efficiency approaching 100%, which means the light-to-carrier and then the following carrier transportation and extraction are no longer limiting factors in photoelectric conversion efficiency of perovskite solar cells. However, the optimal efficiency is still far lower than the Shockley-Queisser efficiency limit, especially for those inverted perovskite solar cells, indicating that a significant fraction of light does not transmit into the active perovskite layer to be absorbed there. Here, a planar inverted perovskite solar cell (ITO/PTAA/perovskite/PC61BM/bathocuproine (BCP)/Ag) is chosen as an example, and we show that its external quantum efficiency (EQE) can be significantly improved by simply texturing the poly[bis (4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) layer. By washing the film prepared from a mixed polymer solution of PTAA and polystyrene (PS), a textured PTAA/perovskite interface is introduced on the light-input side of perovskite to inhibit internal optical reflection. The reduction of optical loss by this simple texture method increases the EQE and then the photocurrent of the ITO/PTAA/perovskite/PC61BM/BCP/Ag device with the magnitude of about 10%. At the same time, this textured PTAA benefits the band edge absorption in this planar solar cell. The large increase of the short-circuit current together with the increase of fill factor pushes the efficiency of this inverted perovskite solar cell from 18.3% up to an efficiency over 20.8%. By using an antireflection coating on glass to let more light into the device, the efficiency is further improved to 21.6%, further demonstrating the importance of light management in perovskite solar cells.

Efficient and Stable Planar n-i-p Perovskite Solar Cells with Negligible Hysteresis through Solution-Processed Cu2 O Nanocubes as a Low-Cost Hole-Transport Material.

Organic-inorganic halide perovskite solar cells (PSCs) have reached certified efficiencies of over 23 % with expensive organic hole-transporting materials. However, the use of an inorganic hole-transport layer (HTL) remains crucial as it would reduce cost combined with higher mobility and stability. In this direction, the application of Cu2 O as the top layer in PSCs is still complicated owing to the difficulty of solution processing. Herein, a solution-processing method is reported for preparing Cu2 O nanocubes as a p-type HTL in regular structure (n-i-p) PSCs. The controlled synthesis of Cu2 O nanocubes in a size range of 60-80 nm is achieved without using any surfactants, which are usually toxic and tricky to remove. The new structure of these Cu2 O nanocubes enhances the carrier mobility with preferable energy alignment to the perovskite layer and superb stability. The PSCs based on these Cu2 O nanocubes HTMs could achieve an efficiency exceeding 17 % with high stability, whereas organic P3HT-based PSCs display an efficiency of 15.59 % with a poorer running stability. This indicates that Cu2 O nanocubes are a promising HTM for efficient and stable PSCs.

High Open-Circuit Voltage of 1.134 V for Inverted Planar Perovskite Solar Cells with Sodium Citrate-Doped PEDOT:PSS as a Hole Transport Layer.

Poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) plays an important role in inverted planar perovskite solar cells (IPPSCs) as an efficient hole extraction and transfer layer (HTL). The IPPSCs based on PEDOT:PSS normally display inferior performance with a reduced open-circuit voltage. To address this problem, here sodium citrate-doped PEDOT:PSS is adopted as an effective HTL for improving the performance of IPPSCs. Sodium citrate-doped PEDOT:PSS HTL improves the conversion efficiency of IPPSCs from 15.05% of reference cells to 18.39%. The large increase of the open-circuit voltage ( VOC) from 1.057 to 1.134 V is the main source for this performance enhancement. With the help of characterization analysis of ultraviolet photoelectron spectroscopy, scanning electron microscopy, electrochemical impedance spectroscopy, etc., the higher work function of the doped PEDOT:PSS film and the uniform crystallinity of the perovskite film on it are disclosed as the reasons for the increased VOC and the consequent performance enhancement.

Erratum: Superior Stability and Efficiency Over 20% Perovskite Solar Cells Achieved by a Novel Molecularly Engineered Rutin-AgNPs/Thiophene Copolymer.

[This corrects the article DOI: 10.1002/advs.201800568.].

Superior Stability and Efficiency Over 20% Perovskite Solar Cells Achieved by a Novel Molecularly Engineered Rutin-AgNPs/Thiophene Copolymer.

Perovskite solar cells (PSCs) with efficiencies greater than 20% have been realized mostly with expensive spiro-MeOTAD hole-transporting material. PSCs are demonstrated that achieve stabilized efficiencies exceeding 20% with straightforward low-cost molecularly engineered copolymer poly(1-(4-hexylphenyl)-2,5-di(thiophen-2-yl)-1H-pyrrole) (PHPT-py) based on Rutin-silver nanoparticles (AgNPs) as the hole extraction layer. The Rutin-AgNPs additive enables the creation of compact, highly conformal PHPT-py layers that facilitate rapid carrier extraction and collection. The spiro-MeOTAD-based PSCs show comparable efficiency, although their operational stability is poor. This instability originated from potential-induced degradation of the spiro-MeOTAD/Au contact. The addition of conductive Rutin-AgNPs into PHPT-py layer allows PSCs to retain >97% of their initial efficiency up to 60 d without encapsulation under relative humidity. The PHPT-py/ Rutin-AgNPs-based devices surpass the stability of spiro-MeOTAD-based PSCs and potentially reduce the fabrication cost of PSCs.

Computational Study of Ternary Devices: Stable, Low-Cost, and Efficient Planar Perovskite Solar Cells.

Although perovskite solar cells with power conversion efficiencies (PCEs) more than 22% have been realized with expensive organic charge-transporting materials, their stability and high cost remain to be addressed. In this work, the perovskite configuration of MAPbX (MA = CH3NH3, X = I3, Br3, or I2Br) integrated with stable and low-cost Cu:NiO x hole-transporting material, ZnO electron-transporting material, and Al counter electrode was modeled as a planar PSC and studied theoretically. A solar cell simulation program (wxAMPS), which served as an update of the popular solar cell simulation tool (AMPS: Analysis of Microelectronic and Photonic Structures), was used. The study yielded a detailed understanding of the role of each component in the solar cell and its effect on the photovoltaic parameters as a whole. The bandgap of active materials and operating temperature of the modeled solar cell were shown to influence the solar cell performance in a significant way. Further, the simulation results reveal a strong dependence of photovoltaic parameters on the thickness and defect density of the light-absorbing layers. Under moderate simulation conditions, the MAPbBr3 and MAPbI2Br cells recorded the highest PCEs of 20.58 and 19.08%, respectively, while MAPbI3 cell gave a value of 16.14%.

A novel magnetite nanorod-decorated Si-Schiff base complex for efficient immobilization of U(vi) and Pb(ii) from water solutions.

A novel silicon Schiff base complex (Si-SBC) and magnetite nanorod-decorated Si-SBC (M/SiO2-Si-SBC) were synthesized and well characterized in detail. The synthesized materials were applied for the removal of U(vi) and Pb(ii) from water solutions under various experimental conditions. The monolayer maximum adsorption capacities of M/SiO2-Si-SBC (6.45 × 10-4 mol g-1 for Pb(ii) and 4.82 × 10-4 mol g-1 for U(vi)) obtained from the Langmuir model at 25 °C and pH = 5.00 ± 0.05 were higher than those of Si-SBC (5.18 × 10-4 mol g-1 for Pb(ii) and 3.70 × 10-4 mol g-1 for U(vi)). Moreover, DFT calculations showed that the high adsorption energies (Ead) of 7.61 kcal mol-1 for Pb2+-(Si-SBC) and 2.72 kcal mol-1 for UO22+-(Si-SBC) are mainly attributed to stronger electrostatic interactions. The results revealed that the Si-SBC and M/SiO2-Si-SBC could be used as efficient adsorbents for the effective elimination of U(vi) and Pb(ii) from contaminated wastewater. High sorption capacity and reusability indicated the practical applications of the synthesized materials in environmental pollution cleanup.

Ion-Migration Inhibition by the Cation-π Interaction in Perovskite Materials for Efficient and Stable Perovskite Solar Cells.

Migration of ions can lead to photoinduced phase separation, degradation, and current-voltage hysteresis in perovskite solar cells (PSCs), and has become a serious drawback for the organic-inorganic hybrid perovskite materials (OIPs). Here, the inhibition of ion migration is realized by the supramolecular cation-π interaction between aromatic rubrene and organic cations in OIPs. The energy of the cation-π interaction between rubrene and perovskite is found to be as strong as 1.5 eV, which is enough to immobilize the organic cations in OIPs; this will thus will lead to the obvious reduction of defects in perovskite films and outstanding stability in devices. By employing the cation-immobilized OIPs to fabricate perovskite solar cells (PSCs), a champion efficiency of 20.86% and certified efficiency of 20.80% with negligible hysteresis are acquired. In addition, the long-term stability of cation-immobilized PSCs is improved definitely (98% of the initial efficiency after 720 h operation), which is assigned to the inhibition of ionic diffusions in cation-immobilized OIPs. This cation-π interaction between cations and the supramolecular π system enhances the stability and the performance of PSCs efficiently and would be a potential universal approach to get the more stable perovskite devices.

Copper-Substituted Lead Perovskite Materials Constructed with Different Halides for Working (CH3NH3)2CuX4-Based Perovskite Solar Cells from Experimental and Theoretical View.

Toxicity and chemical instability issues of halide perovskites based on organic-inorganic lead-containing materials still remain as the main drawbacks for perovskite solar cells (PSCs). Herein, we discuss the preparation of copper (Cu)-based hybrid materials, where we replace lead (Pb) with nontoxic Cu metal for lead-free PSCs, and investigate their potential toward solar cell applications based on experimental and theoretical studies. The formation of (CH3NH3)2CuX4 [(CH3NH3)2CuCl4, (CH3NH3)2CuCl2I2, and (CH3NH3)2CuCl2Br2] was discussed in details. Furthermore, it was found that chlorine (Cl-) in the structure is critical for the stabilization of the formed compounds. Cu-based perovskite-like materials showed attractive absorbance features extended to the near-infrared range, with appropriate band gaps. Green photoluminescence of these materials was obtained because of Cu+ ions. The power conversion efficiency was measured experimentally and estimated theoretically for different architectures of solar cell devices.