High humidity fabrication of rGO incorporated perovskite absorber and MoS2 electrode for prospective inverted PSC

Methylammonium lead triiodide (MAPbI3) is a perovskite material that is widely used in perovskite solar cells due to its potential for high power conversion efficiency. However, it is sensitive to humid environments, heat, oxygen and UV radiation, which can cause it to degrade and negatively affect crystal growth and the morphology of the material. This can ultimately affect the efficiency of the solar cell. Therefore, MAPbI3 is typically produced at a low humidity, which requires expensive equipment. The aim of this research study is to propose a facile fabrication process for fully solution-processable inverted perovskite solar cells employing reduced graphene oxide (rGO)-based material under high humidity conditions suitable for the weather in Malaysia. Overall, the research design was divided into three phases. The aim of phase 1 is to study the influence of incorporating sulfonated rGO (srGO) into the MAPbI3 absorber layer for the deposition of a high-quality thin film under open-air conditions with high relative humidity. Three different samples were prepared with different weight percentage (wt%) of srGO: 0% (T), 50% (TS B) and 15% (TS D). The morphology of the srGO-MAPbI3 films was improved by the addition of srGO, resulting in fewer defects and larger perovskite grain sizes approaching micron size. In phase 2, the study aimed to determine the optimal process parameter of molybdenum disulfide (MoS2) composite with rGO as a viable solution-processed top electrode for an effective electron-collecting electrode by taking advantage of Taguchi analysis. The results of the Taguchi analysis showed that a ratio of rGO:MoS2 (1:1), a heating temperature of 75°C, and a heating period of 15 minutes were the optimal parameters for the electrode manufacturing process. The discovered optimal parameters were deployed to fabricate rGO:MoS2 composite electrode that showed a promising electrical conductivity of 9.36 Ω/sq. In phase 3, the device performance of the inverted perovskite solar cells with the designated configuration of ITO/CuSCN/srGO-MAPbI3/PCBM/BCP/rGO-MoS2 was analyzed by numerical simulation with SCAPS-1D. The results proved that the device performance for the samples was affected by the addition of srGO to the absorber layer. The 15% srGO sample exhibited the highest PCE of 10.37% with Ag as the top electrode. However, when the conventional electrode was replaced with a rGO-MoS2 composite electrode, the PCE of the same sample was improved to 13.23%, with a significant increase in FF. In summary, the findings of this research study indicate that incorporation of srGO into the MAPbI3 absorber layer can improve the morphology of the srGO-MAPbI3 films, resulting in fewer defects and larger perovskite grain sizes. The study also provides insight into the use of rGOMoS2 composite material as a workable solution-processed top electrode for an effective electron-collecting electrode, particularly in inverted configuration of perovskite solar cells. The numerical simulation results showed that the device performance of the samples could be improved by replacing Ag with rGO-MoS2. The findings of this study could have significant implications for the growth of cost-effective, solution-processed perovskite solar cells under high relative humidity

Understanding the structural properties of feasible chemically reduced graphene

The production of pristine graphene materials for industrialization, often limited by the complicated synthesis route, has introduced other graphene derivatives with a workable and facile synthesis route, especially for mass production. For the chemical exfoliation process, the synthesis involves oxidants and reducing agents to exfoliate the graphene layer from the 3D graphite and remove excess oxygen-containing functional groups yielding graphene-like materials known as reduced graphene oxide (rGO). This work feasibly produces rGO with nanoplatelet morphology through the green solution-processable method. Upon reduction, the crystallite size for the a-axis (La) is more prominent (22.50 Å) than the crystallite size for the c-axis (Lc) (11.50 Å), suggesting the nanoplatelets structure of the end product, which is also confirmed by the morphology. The integrated intensity (ID/IG) ratio and average defect density (nD) of as-prepared rGO confirmed the sp2 restoration in the graphitic structure. Overall, the Raman and X-ray diffraction (XRD) characterization parameters validate the production of rGO nanoplatelets, especially with four graphene layers per domain, suggesting that high-quality rGO are achievable and ready to be implemented for the large-scale production

Effect of sulfur content in the crude oil to the corrosion behavior of internal sur-face of API 5L X65 petroleum pipeline steel

This work discussed the corrosion behaviour of the internal surface of pipeline steel caused by petroleum products’ composition, particularly crude oil. Internal and external pipeline corrosion is the notable cause of pipeline failure in Malaysia’s oil and gas industry. However, internal corrosion is preferred to be concerned in this work because it involved one of the significant corrosive media in crude oil, such as sulfur content. This project aims to find the sulfur concentration in the crude oil using Fourier transform infrared spectroscopy and atomic absorption spectroscopy. The corrosion rate, corrosion current and corrosion potential of the API 5L X65 grade carbon steel pipeline in different simulated H2SO4 solution concentrations were carried out using the Tafel extrapolation technique. The samples’ corrosion properties were morphologically measured through the optical microscope, scanning electron microscope, and energy dispersive X-ray analyses. The results showed pipeline steel’s corrosion rate significantly increased with increasingH2SO4 concentrations. The corrosion products formed on the pipeline steel surfaces were mainly composed of iron sulphate, iron sulphide, and iron oxide. These findings are crucial to understanding the corrosion behaviour caused by crude oil and should be further investigated with the other influential factors such as temperature and petroleum flowing velocity

Recent progress of electrode architecture for MXene/MoS2 supercapacitor: preparation methods and characterizations

Since their discovery, MXenes have conferred various intriguing features because of their distinctive structures. Focus has been placed on using MXenes in electrochemical energy storage including a supercapacitor showing significant and promising development. However, like other 2D materials, MXene layers unavoidably experience stacking agglomeration because of its great van der Waals forces, which causes a significant loss of electrochemically active sites. With the help of MoS2, a better MXene-based electrodecan is planned to fabricate supercapacitors with the remarkable electrochemical performance. The synthesis of MXene/MoS2 and the ground effects of supercapacitors are currently being analysed by many researchers internationally. The performance of commercial supercapacitors might be improved via electrode architecture. This analysis will support the design of MXene and MoS2 hybrid electrodes for highly effective supercapacitors. Improved electrode capacitance, voltage window and energy density are discussed in this literature study. With a focus on the most recent electrochemical performance of both MXene and MoS2-based electrodes and devices, this review summarises recent developments in materials synthesis and its characterisation. It also helps to identify the difficulties and fresh possibilities MXenes MoS2 and its hybrid heterostructure in this developing field of energy storage. Future choices for constructing supercapacitors will benefit from this review. This review examines the newest developments in MXene/MoS2 supercapacitors, primarily focusing on compiling literature from 2017 through 2022. This review also presents an overview of the design (structures), recent developments, and challenges of the emerging electrode materials, with thoughts on how well such materials function electrochemically in supercapacitors

Co-sensitization of natural sensitizers extracted from rengas (Gluta spp.) and mengkulang (Heritiera elata) wood with ruthenium dye (N719) to enhance the performance of dye-sensitized solar cells

In this study, photovoltaic performance was improved when two natural sensitizers, namely, rengas (Gluta spp.) and mengkulang (Heritiera elata), were mixed with ruthenium (N719) sensitizer. Five different ratios were prepared and their performances were compared with individual sensitizers. The components of the sensitizers were analyzed via ultraviolet–visible spectrophotometry and Fourier transform infrared spectroscopy. The band gap values and the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO-LUMO) levels were calculated using data obtained from photoluminescence analysis and cyclic voltammetry. The mengkulang: N719 (80%:20%) sensitizer exhibits the highest conversion efficiency (ŋ), which is 0.58% with an open circuit voltage (Voc) of 0.63 V, a short circuit photocurrent density (Jsc) of 2.1 mA/cm2, and a fill factor (ff) of 0.44. By contrast, the individual mengkulang sensitizer presents a poor conversion efficiency (ŋ) of 0.16%

A comprehensive review of filler, plasticizer, and ionic liquid as an additive in GPE for DSSCs

Low ionic conductivity in gel polymer electrolytes (GPEs) affects low dye-sensitized solar cells (DSSCs) performance is a crucial issue. Generally, the GPEs contain polymer (act as solvent holder), solvent, and salt (as ions provider). Usually, the GPE-based DSSCs are assembly with three necessary compartments: working electrode, GPE, and platinum electrode. The DSSCs parameters are included open-circuit voltage, Voc; short-circuit current density, Jsc; fill factor, ff and efficiency, %. This review's main objective was to explore an additive such as plasticizer, filler, and ionic liquid effects on the ionic conductivity in GPEs by improving ions mobility and expanding the free volume of the GPE. The impact of additives in the GPE is also expected to enhance the DSSCs performance by increasing the Jsc, Voc, ff, and efficiency. This comprehensive review discussed the latest progress of GPE utilizing the additive by listing the literature from the recent ten years

Characterization of reduced graphene oxide/activated carbon-based electrode containing mixing CMC-SBR binder and application in supercapacitor

In this work, variation of mixing a combination of carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) as both used as the binder in the electrode has been studied. The purpose of using CMC-SBR as the binder in the electrode is to achieve a high supercapacitor performance. The electrode preparation has been carried out by mixing the reduced graphene oxide (rGO) and activated carbon (AC) in a blender. The binder preparation started by dissolving the CMC and SBR in the deionized water using a clean glass container. Then, rGO/AC has been stirred with the CMC-SBR for 60 minutes until a homogenous slurry formed. All electrodes have been characterized with Raman spectroscopy. The electrochemical tests such as cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) for all electrode compositions were performed. The electrode with 4:6 (in weight percentage) of CMC-SBR shows the highest specific capacitance (Csp) of 59.65 F g-1 (CV scan rate of 1 mV s-1) and 12.82 F g-1 from GCD test. This confirmed that the electrode containing 4 wt.% of CMC and 6 wt.% of SBR resulting in the best composition, which is reliable and practical for the supercapacitor application

Electron transport studies of dye-sensitizer solar cells based on natural sensitizer extracted from rengas (Gluta spp.) and mengkulang (Heritiera elata) wood

Dyes extracted from rengas (Gluta spp.) and mengkulang (Heritiera elata) wood were investigated as sensitizers in dye-sensitized solar cells (DSSCs). Three types of sensitizers, including individual sensitizer, mixture sensitizer, and co-sensitizer, exhibited different patterns of absorption properties under UV-Vis spectroscopy. The incident photon-to-current efficiency (IPCE) was analyzed via spectral response to examine the generation of photocurrent. Because mixture sensitized DSSCs obtained broader absorption spectra, they were expected to achieve good light harvesting and hence, enhanced photocurrent and conversion efficiency. The photovoltaic performance was further examined by electrochemical impedance spectroscopy (EIS). The mixture sensitized DSSCs exhibited good conversion efficiency (0.21% and 0.30%) compared with individual sensitized DSSCs (0.16% and 0.11%). The co-sensitized DSSCs also showed increased conversion efficiency with ruthenium (N719) dye as a co-sensitizer. The parameters calculated from EIS analysis were used to determine suitable conditions for the dye to be implemented in DSSC. The behavior of electron transport was determined to be efficient due to the increase of electron diffusion coefficient, electron lifetime, and low recombination rate as achieved by the mixture sensitized DSSCs

A comprehensive review of filler, plasticizer, and ionic liquid as an additive in GPE for DSSCs

Low ionic conductivity in gel polymer electrolytes (GPEs) affects low dye-sensitized solar cells (DSSCs) performance is a crucial issue. Generally, the GPEs contain polymer (act as solvent holder), solvent, and salt (as ions provider). Usually, the GPE-based DSSCs are assembly with three necessary compartments: working electrode, GPE, and platinum electrode. The DSSCs parameters are included open-circuit voltage, Voc; short-circuit current density, Jsc; fill factor, ff and efficiency, %. This review’s main objective was to explore an additive such as plasticizer, filler, and ionic liquid effects on the ionic conductivity in GPEs by improving ions mobility and expanding the free volume of the GPE. The impact of additives in the GPE is also expected to enhance the DSSCs performance by increasing the Jsc, Voc, ff, and efficiency. This comprehensive review discussed the latest progress of GPE utilizing the additive by listing the literature from the recent ten years

Direct Observation Of Graphene During Raman Analysis And The Effect Of Precursor Solution Parameter On The Graphene Structures

Controlling the precursor solution parameter in preparing active catalyst film is critical in sol-gel process. The aim of this work is to validate the precursor solution parameter that affects the structural properties of graphene. Active Co3O4 film was prepared using precursor solution from cobalt acetate tetrahydrate in two different concentrations; 0.025 M and 0.05 M. One batch of the precursor solution was directly spin coated onto the substrate's surface meanwhile the second batch was kept for 4 days aging process. The studied spin speeds were 2000 rpm and 6000 rpm, and spin coated for 60 s. The active Co3O4 film was achieved by annealing at 450 °C and the graphene was grown at 900 °C of chemical vapor deposition (CVD) processing temperature for 5 min with the presence of ethanol as the carbon feedstock. The structural properties and morphology of the as-grown graphene synthesized from active Co3O4 film were characterized by Raman spectroscopy, optical microscope, and field emission scanning electron microscope (FESEM). The results demonstrated that concentration of precursor solution and the aging process affected the performance of the as-grown graphene. Agglomerates were formed in sample with 0.05 M of Co acetate tetrahydrate, however it was found that the Raman peaks intensity increased as compared to the 0.025 M sample. The precursor with 0.05 M has an acceptable chemical stability though aged for 4 days and contributed to the graphene growth. The spin coating speed was found not to affect the graphene growth at all. For aging effect, concentration 0.025 M shows unstable condition as compared to concentration 0.05 M when the precursor solution was aged for 4 days. Nonetheless, for the quality of the as-grown graphene, the ratio of Raman 2D-band over G-band intensities was less than 1.0, indicated that the graphene was in multi-layer form