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Geopolymer materials, alternatives to cement that are synthesized using industrial byproducts, have emerged as some of the leading champion materials due to their environmentally friendly attributes. They can significantly reduce pollution by utilizing a plethora of waste products and conserving natural resources that would otherwise be used in the production of conventional cement. Much work is being carried out to study geopolymers' characteristics under different conditions. Here, a geopolymer derived from fly ash (FA) was synthesized using a combination of sodium silicate and potassium hydroxide (KOH) (2.5:1 ratio) as an alkali activator (AA) liquid. The FA/AA ratios were optimized, resulting in distinct geopolymer samples with ratios of 1.00, 1.25, 1.50, and 1.75. By adjusting the contribution of alkaline liquid, we investigated the impacts of subtle changes in the FA/AA ratio on the morphology and microstructure using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. The FESEM analysis illustrated a mixed matrix and morphology, with the sample with a ratio of 1.00 displaying consistently fused and homogenous morphology. The XRD results revealed the prevalent amorphous nature of geopolymer with a few crystalline phases of quartz, sodalite, hematite, and mullite. An electrical study confirmed the insulating nature of the geopolymer samples. Insulating geopolymers can provide energy-efficient buildings and resistance to fire, hurricanes, and tornadoes. Additionally, using KOH as a part of the alkali activator introduced a less-explored aspect compared to conventional sodium hydroxide-based activators, highlighting the novelty in the synthesis process. [ABSTRACT FROM AUTHOR]

This work mainly focuses on synthesizing and evaluating the efficiency of methylammonium lead halide‐based perovskite (MAPbX3; X=Cl, Br, I) solar cells. We used the colloidal Hot‐injection method (HIM) to synthesize MAPbX3 (X=Cl, Br, I) perovskites using the specific precursors and organic solvents under ambient conditions. We studied the structural, morphological and optical properties of MAPbX3 perovskites using XRD, FESEM, TEM, UV‐Vis, PL and TRPL (time‐resolved photoluminescence) characterization techniques. The particle size and morphology of these perovskites vary with respect to the halide variation. The MAPbI3 perovskite possesses a low band gap and low carrier lifetime but delivers the highest PCE among other halide perovskite samples, making it a promising candidate for solar cell technology. To further enrich the investigations, the conversion efficiency of the MAPbX3 perovskites has been evaluated through extensive device simulations. Here, the optical constants, band gap energy and carrier lifetime of MAPbX3 were used for simulating three different perovskite solar cells, namely I, Cl or Br halide‐based perovskite solar cells. MAPbI3, MAPbBr3 and MAPbCl3 absorber layer‐based devices showed ~13.7 %, 6.9 % and 5.0 % conversion efficiency. The correlation between the experimental and SCAPS simulation data for HIM‐synthesized MAPBX3‐based perovskites has been reported for the first time. [ABSTRACT FROM AUTHOR]

Sb2Se3, a promising thin‐film photovoltaic (TFPV) absorber material known for its non‐toxic nature, abundance on Earth, and stability has the inherent limitations of low doping density of 1013 cm−3 and poor carrier mobility of 1.5 cm2 V−1 s−1, leading to a low built‐in potential and inefficient carrier collection. To address these challenges and enhance the built‐in potential and carrier collection, an effective hole‐transport layer (HTL), e.g. CdS, which contains toxic components is used. A less‐toxic alternative is explored: ZnSe as the electron‐transport layer (ETL) to mitigate this issue. In this study, the performance is evaluated of Sb2Se3/ZnSe solar cells using six different HTLs (CuSCN, MoSe2, NiO, Spiro‐OMeTAD, SnS, MoOx) through the utilization of the SCAPS‐1D modeling tool. The HTL plays a critical role in improving the effectiveness of the built‐in potential, enhancing carrier collection, and suppressing back surface recombination. The analysis involves varying the thickness and doping concentration of the absorber, buffer, and HTLs, and exploring the impact of temperature, series and shunt resistance, and the metal work function of the back contact. Among the tested devices, the one with NiO as the HTL demonstrates the highest efficiency, exhibiting a VOC (open‐circuit voltage) of 0.81 V and a PCE (power conversion efficiency) of 24.07%. [ABSTRACT FROM AUTHOR]

The development of multifunctional devices could represent a significant advancement in meeting the need for nano and micro technologies. Therefore, we have developed a Ag/Sb2Se3/FTO-based multifunction device having nanostructures, which works as an ultraviolet (UV) photodetector and a switching device. Our theory suggests how oxygen formation leads to detection in the UV range rather than detection in the infrared range, which is the natural detection range of Sb2Se3. The m–s–m photodetector device is based on the photoconductive phenomenon, and ultrafast transient absorption spectroscopy has been extensively used to investigate the charge carrier dynamics of Sb2Se3 films of 500 nm. At two distinct excitations, 375 nm UV and 532 nm visible light, and a pulse energy of 1 J per pulse, the effect of annealing on the charge carrier relaxation of the films was investigated. The kinetics of the hot charge carrier's decay and recombination were studied for both as-grown and annealed films. The proposed theory is analyzed with the help of X-ray photoelectron spectroscopy and density functional theory studies. The device shows external quantum efficiency values of 2.9 and 1.3 at 375 and 386 nm, respectively. The rise time to fall time ratio was 0.29/0.30 s at 375 nm irradiation at 2 V bias at a power density of 32 mW/cm2. The same device shows bipolar resistive switching, in which resistance shifts from a high resistance state to a low resistance state in a voltage sweep from −1 to 0 V and then 0 to 1 V. The result of the switching phenomenon is reasonably justified by the electrochemical metallization phenomenon. An outstanding accomplishment in electronic devices is combining two different features on a single device. [ABSTRACT FROM AUTHOR]

Antimony selenide (Sb2Se3) material has been brought into sharp focus in the solar cell field due to its remarkable performance in recent times. Solar cell efficiency increases daily because of the excellent properties of Sb2Se3 material and progressive optimisation of each layer, especially the hole-transporting layer (HTL); it suppresses the recombination of the back surface and increases the built-in potential and efficiency. In this work, we used Sb2Se3 as an absorber layer and compared the behaviour of typical hole transport materials (HTMs) (Spiro-OMeTAD, CuSCN, and CuI) and their influence on device performance. The Sb2Se3 photovoltaic model with different HTMs was studied by SCAPS (version 3.3.10) software. Efficiency is highly influenced by light source and intensity. Thickness and defect density of the Sb2Se3 layer, the work function of the back contact, and series and shunt resistances also play an essential role in the better execution of solar cells. The performance of the device is enhanced when the transmission percentage increases at the front contact. The metalwork function must be 5 eV to attain a highly efficient PV cell, and after optimisation, CuI is the best HTM with a 23.48% efficiency. [ABSTRACT FROM AUTHOR]

Optimizing thin‐film‐based solar cells' efficiency is essential for expanding renewable energy deployment. Fundamental device properties such as life‐span and optical properties must be enhanced simultaneously to reduce recombination and losses. Herein, the design and numerical study of an efficient Sb2Se3‐based dual heterojunction (n‐ZnSe/p‐Sb2Se3/p+‐MoSe2) photovoltaic cell with the help of SCAPS‐1D simulation software by using the physical parameters of various layers are presented. The thickness and doping of each layer are considered during the optimization of the device. The work functions of back and front contact also affect the overall performance. Defects in each layer and interface defects are highly responsible for the increment in series resistance. Thus, these defects are also studied. The efficiency improved significantly from 22.52% to 24.57% when MoSe2 is used as a back surface field (BSF) layer. The results demonstrate that the addition of BSF significantly increased the open‐circuit voltage, short‐circuit current density, and fill factor, all of which are within the Shockley–Queisser limits of a dual heterojunction solar cell. This study indicates the possibility of producing highly efficient Sb2Se3 heterojunction‐based solar cells. [ABSTRACT FROM AUTHOR]

The controlled and efficient formation of oxygen vacancies on the surface of metal oxide semiconductors is required for their use in gas sensors. This work addresses the gas-sensing behaviour of tin oxide (SnO2) nanoparticles for nitrogen oxide (NO2), NH3, CO, and H2S detection at various temperatures. Synthesis of SnO2 powder and deposition of SnO2 film is conducted using sol-gel and spin-coating methods, respectively, as these methods are cost-effective and easy to handle. The structural, morphological, and optoelectrical properties of nanocrystalline SnO2 films were studied using XRD, SEM, and UV-visible characterizations. The gas sensitivity of the film was tested by a two-probe resistivity measurement device, showing a better response for the NO2 and outstanding low-concentration detection capacity (down to 0.5 ppm). The anomalous relationship between specific surface area and gas-sensing performance indicates the SnO2 surface's higher oxygen vacancies. The sensor depicts a high sensitivity at 2 ppm for NO2 with response and recovery times of 184 s and 432 s, respectively, at room temperature. The result demonstrates that oxygen vacancies can significantly improve the gas-sensing capability of metal oxide semiconductors. [ABSTRACT FROM AUTHOR]

As a promising solar absorber material, antimony selenide (Sb2Se3) has gained popularity. However, a lack of knowledge regarding material and device physics has slowed the rapid growth of Sb2Se3-based devices. This study compares the experimental and computational analysis of the photovoltaic performance of Sb2Se3-/CdS-based solar cells. We construct a specific device that may be produced in any lab using the thermal evaporation technique. Experimentally, efficiency is improved from 0.96% to 1.36% by varying the absorber's thickness. Experimental information on Sb2Se3, such as the band gap and thickness, is used in the simulation to check the performance of the device after the optimization of various other parameters, including the series and shunt resistance, and a theoretical maximum efficiency of 4.42% is achieved. Further, the device's efficiency is improved to 11.27% by optimizing the various parameters of the active layer. It thus is demonstrated that the band gap and thickness of active layers strongly affect the overall performance of a photovoltaic device. [ABSTRACT FROM AUTHOR]