Enhanced multifunctionality of CuO nanoparticles synthesized using aqueous leaf extract of Vernonia amygdalina plant

We report the synthesis of medicinal plant, Vernonia amygdalina Del. mediated green copper oxide nanoparticles (VeA-CuO NPs). The presence of two absorbance maxima, λmax 1 and λmax 2 at 436 nm and 452 nm, respectively confirms a mixture of biomolecules surface amalgamated CuO NPs with different morphological features. The FT-IR spectra of the plant leaf extract and VeA-CuO confirmed the efficient role of biomolecules as capping and stabilising agents. The XRD patterns of NPs approved high crystallinity of CuO. The purity of the NPs was corroborated by SEM-EDAX analysis. The average particle size of the NPs was found to be 19.68 nm. In addition, the combined TEM, HRTEM and SAED analysis substantiated the presence of CuO with a d-spacing value of 0.2854 nm, which conformed to CuO (1 1 1). The antibacterial assay revealed that VeA-CuO NPs were synergistic in their influence versus bacterial strains, S. aureus, E. coli, P. aeruginosa, and E. aerogenes. The uppermost zone of inhibition of 15 mm was observed for E. aerogenes. The bioactive compounds capped around the CuO NPs served the effective role in disrupting the cell wall of bacterial strains. The degradation efficiencies for Indigo carmine (IC) and Malachite green (MG) dyes by NPs were found to be 95% and 91%, respectively. The lowest degradation half-life was recorded to be 16.55 min for MG dye. In addition, the better electrode stability revealed by CV and EIS studies, confirms the multi-functional nature of VeA-CuO NPs, these CuO NPs exhibited multifunctional applications

Short-term light soaking effect on dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) are one of the most promising third generation solar cells and have been regarded as a competitive alternative to the conventional siliconbased photovoltaic devices due to their relatively low production cost. Light soaking effect is an intriguing phenomenon that exists in DSSCs, which refers to the enhancement of the electrical parameters in the cells after being exposed to light soaking. In this paper, we report on the variation in the electrical parameters of DSSCs under continuous exposure to a simulated solar irradiation for a period up to 6h. Increments of Jsc and Voc in DSSC were observed after 6h of light soaking, which led to improved efficiency from 3.87% to 4.50%. The improvements may be ascribed to the formation of electron trapping states below the TiO2 conduction band edge, which facilitated the charge carrier transport

A Review on Semitransparent Solar Cells for Real-Life Applications Based on Dye-Sensitized Technology

A dye-sensitized solar cell (DSSC) is one of the emerging photovoltaic technologies that shows promising prospects in the commercial applications because of its semitransparency, low manufacturing cost, facile fabrication procedures, and good performance under low-light conditions. Despite the aforementioned advantages of DSSC technology, the transition from laboratory to industrial applications is hindered by several major obstacles. This article aims to explore the potential of DSSC technology in real-life applications, namely, building-integrated photovoltaic, indoor energy harvesting, and smart farming, and the research challenges that must be overcome to pave the way for DSSC commercialization. The challenges can be categorized into the long-term stability issue and difficulty related to the scale-up processes. This article also presents insights into the potentials of DSSCs in smart farming and controlled-environment agriculture, which were never been reported before

Synthesis of dye-sensitised solar cells utilising platinised counter electrode

In this work, the influences of catalyst materials of counter electrodes – carbon (C) and platinum (Pt) electrodes, transparent conducting oxide (TCO) substrates – fluorine-doped tin oxide (FTO) and indium-doped tin oxide (ITO) glasses and dyes (N3 and N719 dyes) on the photovoltaic performance of dye-sensitised solar cells (DSCCs) were investigated. DSSC was fabricated with standard configuration: a mesoporous TiO2 layer (15–20 nm particle size, anatase phase) deposited on ITO/FTO glass as photoanode, N3/N719 (Solaronix) as dyes, chenodeoxycholic acid as co-adsorbent in dye solution, Pt-coated/C-coated glass as counter electrode and Iodolyte AN-50 (Solaronix) as electrolyte. The optimised DSSC demonstrated photovoltaic performance of short-circuit photocurrent density (Jsc) of 8.36 mA/cm2, open-circuit photovoltage (Voc) of 0.69 V and a fill factor (FF) of 0.70, corresponding to power conversion efficiency (PCE) of 4.05% under simulated air mass 1.5 solar light condition

Efficiency Enhancement in Dye-Sensitized Solar Cells with ZnO and TiO2 Blocking Layers

Dye-sensitized solar cells (DSSCs) have great potential for solar generation owing to their low cost and ease of fabrication compared with silicon-based photovoltaic devices. One of the major issues with TiO2-based DSSCs is the recombination loss at the substrate–electrolyte interface due to the mesoporous nature of the TiO2 film. It was proposed earlier that introduction of a blocking layer at the substrate–TiO2 interface could reduce this recombination loss by preventing direct contact of the substrate and electrolyte. In this study, ZnO blocking layers (ZBLs) with different thicknesses were spin-coated onto fluorine-doped tin oxide (FTO) glass and the influence studied in comparison with a conventional TiO2 blocking layer (TBL) prepared using the same technique. The ZBL functions as an energy barrier at the FTO–electrolyte interface to prevent backtransfer of electrons to the electrolyte from the FTO. The blocking effect of the ZBL was verified by an enhancement of the fill factor (FF) and open-circuit photovoltage (Voc) of the DSSC, leading to an improvement in the power conversion efficiency (PCE) from 3.86% to 4.34% for the ZBL with optimum thickness of 120 nm. The suppression of the dark current density revealed a reduction of charge recombination with increasing ZBL thickness. Further increase in the ZBL thickness resulted in reduced cell performance due to a drastic decrease of the short-circuit current density (Jsc). The PCE was slightly improved to 4.36% by replacing the ZBL with a 100-nm TBL. These results suggest that the facile and low-cost sol–gel spin-coating technique is a feasible method for formation of a ZBL or TBL to reduce the recombination loss in DSSCs

Optimising performances of LoRa based IoT enabled wireless sensor network for smart agriculture

The significance of maintaining food security is particularly emphasized in regions such as Malaysia, where there is a substantial reliance on imports of fruits and vegetables. The local farming industry requires advancements in technology to address the complexities of food production. This motivates the exploration of implementing Internet of Things (IoT) solutions to reduce reliance on manpower and enhance farming efficiency. However, the current integrated IoT solutions for smart farms can be expensive and complicated, rendering them redundant for small-area farms that do not require advanced technologies or machine learning. This study aims to optimize IoT LoRa parameter settings, focusing on providing affordable solutions tailored for fruit and vegetable farms. The main goal is to address the common issue faced by farmers—investing in expensive IoT-enabled wireless sensors without realizing a return on investment. To overcome this challenge, a simple and cost-effective IoT solution is proposed, utilising sensors and readily available applications to achieve efficient farming practises. The main objective is to develop an integrated IoT solution tailored for fruit and vegetable farms, facilitating improved productivity and growth. The solution incorporates sensors to monitor and control various aspects of crop cultivation, collecting essential data. The research development here also aims to inspire low-cost IoT solutions suitable for small-scale food plantation farms by using the long-range physical communication technique (LoRa) protocol. Leveraging IoT technologies in a simplified manner allows local farming industries to boost productivity, lower operational costs, and effectively address food security concerns. In addition to the IoT technology development for smart farms, the research here also investigates the various factors affecting the performance of LoRa-enabled IoT solutions for smart farms, including LoRa frequency, distance, environment, and the performance of the IoT system under different weather conditions, showed a significant effect on system performance (p ≤ 0.05). This comprehensive approach aims to contribute valuable insights for the development and implementation of cost-effective IoT solutions tailored for small-scale agricultural practices. In conclusion, this project demonstrates the efficiency of LoRa-based IoT in agriculture and highlights areas for improvement. Future directions involve improving scalability, streamlining the user interface, and adding sophisticated features to support the development of productive, networked, and environmentally friendly farming methods

Ga-Sn Co-Doped ZnO Films via Sol-Gel Route

Zinc oxide (ZnO) has gained worldwide attention due to its direct wide band gap and large exciton binding energy, which are important properties in the application of emerging optoelectronic devices. By doping ZnO with donor elements, a combination of good n-type conductivity and good transparency in the visible and near UV range can be achieved. Co-doping ZnO with several types of dopants is also beneficial in improving the electronic properties of ZnO films. To the best of our knowledge, the fundamental properties of gallium-tin (Ga-Sn) co-doped ZnO (GSZO) films were rarely explored. In this work, we attempt to coat GSZO films on glass substrates via sol-gel spin-coating method. The Ga-Sn co-doping ratio was fixed at 1:1 and the concentration of the dopants was varied at 0.5, 1.0, 1.5, and 2 at.% with respect to the precursor. The AFM image show granular features on the morphology of all GSZO films. All samples also exhibit a preferential c-axis orientation as detected by XRD. The XRD indicates higher crystal quality and larger crystallite size on GSZO thin films at 2.0 at.% and agrees well with the AFM results. However, the transparency and optical band-gap of the GSZO thin films degrade with higher co-doping concentration. The best electrical properties were achieved at co-doping concentration of 1 at.% with conductivity and carrier density of 7.50 × 10-2 S/cm and 1.37 × 1016 cm-3, respectively. At 1.0 at.% co-doping concentration, optimal optical transmittance and electrical properties were achieved, making it promising in the application of optoelectronics

Effect of precursor solution stirring time on the electrochromic performance of tungsten oxide films

Tungsten oxide (WO3) is an n-type semiconductor with a wide range of transparent electronic applications such as smart windows, rear-view displays and gas sensors. In this work, WO3 films were prepared on tin doped indium oxide (ITO) coated glasses by utilising the sol–gel spin-coating method. The effect of WO3 precursor solution stirring time (3, 10 and 24 h) on the electrochromic (EC) properties of WO3 films was investigated. The optical transmittance of the WO3 films in the visible range decreased as precursor stirring time was increased. The WO3 films subjected to 3 and 10 h of stirring had a large optical modulation compared to the WO3 films subjected to 24 h of stirring. CV results showed higher coloration current in WO3 films subjected to 3 h stirring which is an indication of faster intercalation kinetics. Moreover, it had fast switching time and high coloration efficiency of 34.8 cm2 C–1

Towards an All-Solid-State Electrochromic Device: A Review of Solid-State Electrolytes and the Way Forward

In order to curb high electricity usage, especially in commercial buildings, smart windows, also known as “switchable” or “smart” glasses, have attracted a significant amount of attention in an effort to achieve energy savings in eco-friendly buildings and transportation systems. Smart windows save energy by regulating the input of solar heat and light and hence cutting down air-conditioning expenses, while maintaining indoor comfort. This is achieved by electrochromism, which is defined as the reversible colour change in electrochromic (EC) materials from transparent to dark blue and vice versa under a small applied voltage. Recent state-of-the-art electrochromic devices (ECD) adopt liquid-based electrolytes as the main source of energy for basic operations. While this has resulted in much success in ECDs as reported in past studies, there remain several drawbacks to this aspect, such as liquid electrolyte leakage and evaporation, not to mention safety concerns related to the harmful nature of electrolyte materials. This paper aims to review the recent advances in various solid electrolytes that are potential solutions to the mentioned problems