Mohd Adib Ibrahim

A review of organic small molecule-based hole-transporting materials for meso-structured organic-inorganic perovskite solar cells

This review summarizes the current designs and development of new types of organic small molecules as a hole-transporting material (HTM) in a meso-structured perovskite solar cell (PSC). The roles of each layer in the meso-structured perovskite device architecture are elaborated and the employment of new types of organic HTMs in the device is compared with the commercially available HTM spiro-OMeTAD in terms of the properties, device performance and stability. The studies found that nearly half of the new synthesized and pristine HTMs have comparable or better photovoltaic properties than those of doped spiro-OMeTAD. These HTMs have the characteristics of a fused planar core structure with extended π-conjugated lengths and electron-donating functional groups, which are believed to contribute to their high intrinsic conductivity and help make them an alternative to spiro-OMeTAD as a better HTM in meso-structured PSCs. Some of the devices based on the new synthesized HTMs even have longer device lifetimes than their spiro-OMeTAD-based PSC counterparts. Moreover, studies found that the cost per gram (Cg) and cost-per-peak Watt (Cw) of synthesized HTMs can be reduced via minimizing the number of synthesis steps and by optimization of the starting materials in order to yield low-cost HTMs for meso-structured PSC applications.

Electrodeposited p-type Co3O4 with high photoelectrochemical performance in aqueous medium

p-Type Co3O4 photocathodes with different amounts of CuO, were synthesized on fluorine doped tin oxide (FTO) via electrodeposition from a chloride bath containing suspended starch particles. All of the fabricated samples were photoresponsive toward water splitting in 0.5 M Na2SO4 under simulated sun-light. The PEC performance was evaluated using LSPV, chronoamperometry, and EIS techniques. The samples fabricated via the electrodeposition/anodizing/annealing process showed greater photocurrent response compared to the electrodeposition/annealing process. Among all the samples, the sample with an atomic composition% of Co: 24.9, Cu: 25.0 and O: 50.1 showed an optimum photocurrent response (∼6.5 mA cm−2 vs. SCE at −0.3 V). The structure, morphology/composition and optical response were characterized by XRD, FESEM/EDX and UV-Vis techniques, respectively.

Heterojunction Cr2O3/CuO:Ni photocathodes for enhanced photoelectrochemical performance

Heterojunction p-type photoelectrodes consisting of chromium oxide (Cr2O3) and copper oxide (CuO)-doped nickel (Ni) were prepared using aerosol-assisted chemical vapour deposition (AACVD) and spin-coating. All samples were photoresponsive and showed a photocathodic current in 0.5 M Na2SO4 under simulated solar illumination. The photocathode with an optimal composition of 3 layers of CuO and 0.5% Ni showed an enhanced photoactivity relative to bare Cr2O3. Based on the optical characterization and the flatband potential calculation, the fabricated Cr2O3, Cr2O3/CuO and Cr2O3/CuO:Ni can absorb visible light, which enables the water reduction reaction. Moreover, electrochemical impedance spectroscopy revealed that the charge transfer resistance of Cr2O3/CuO:Ni was decreased. Thus, in the heterojunction structure, the photogenerated electrons in Cr2O3 were transferred to the CuO:Ni layer, which then contributes to a high photoactivity. The combined advantages of the two strategies (heterojunction and doping) provide favourable charge transport characteristics of the materials.

The architecture of the electron transport layer for a perovskite solar cell

The emergence of perovskite solar cells (PSCs) recently has brought new hope to the solar cell industry due to their incredible improvement of the power conversion efficiency (PCE), which can now exceed 20.0% within seven years of tremendous research. The efficiency and stability of PSCs depend strongly on the morphology and type of materials selected as the electron transport layer (ETL) in the device. In this review, the functions of the ETL based on titania (TiO2) in n–i–p architecture PSCs, including planar heterojunction and mesoporous-structured devices, are reviewed in terms of the device performance and stability. Studies found that the application of suitable fabrication techniques and manipulation of the nanostructural properties of TiO2 are crucial factors in ameliorating the short-circuit current density, JSC, and fill factor, FF, of PSCs. On top of that, the effect of substituting TiO2 with other potential inorganic materials like zinc oxide (ZnO), tin oxide (SnO2), ternary metal oxides, and metal sulphides, as well as organic semiconductors including fullerene, graphene, and ionic liquids, towards the photovoltaic properties and stability of the devices are also elaborated and discussed. Meanwhile, the utilization of non-electron transport layers (non-ETLs), such as alumina (Al2O3) and zirconia (ZrO2), as the mesoporous scaffold in PSCs is found to enhance the open-circuit voltage, VOC, of the devices.

Progress towards highly stable and lead-free perovskite solar cells

High-performance perovskite solar cells have attracted increased attention for photovoltaic applications and potentially replacing the predecessor generations. Nevertheless, the stability issues and the lead content has always been among the major concerns that barriers perovskite solar cells from commercialization. This review presents the discussion towards the inherent instability of perovskite solar cells and the development towards replacing lead with discussion towards their performance and challenges. The degradation of perovskite active layer would release toxic substance into the environment. The development towards low-toxic, lead-free and efficient perovskite solar cells is the key for a sustainable solar energy generation with the application of perovskite solar cells.

Metal oxide BiVO4 as photoelectrode in photoelectrochemical solar water oxidation

One of the great challenges facing the society today is replacing fossil fuels by renewable energy sources. Hydrogen from non-carbon sources is considered one of the viable potentials to help alleviate reliance upon fossil fuels for energy and addressing the environmental problems. Photoelectrochemical water splitting was brought to attention since the pioneering work in 1972. Since then, numerous metal oxide photocatalysts have been investigated to enhance the overall water splitting performance. Up to now, Bismuth vanadate, BiVO4 has emerged as the most promising photocatalyst in the construction of photoelectrochemical cell utilizing sunlight and water, the most abundant resources on earth. In this review, the principles, critical factors influencing the efficient BiVO4-based photoanode properties such as the crystal and electronic properties are discussed. Subsequently, the methods synthesis and research efforts adopted to develop efficient and active BiVO4 photoanode are presented.

Kesan tempoh masa enapan terhadap pembentukan elektrod filem nipis kobalt sulfida

Cobalt sulfide counter electrodes (CE) were prepared using the electrodeposition and ionic exchange deposition method on the fluorine doped tin oxide (FTO). Time deposition effect of thin film were analyzed by using a field emission scanning X-ray diffraction (XRD), field emission electron microscope (FESEM), atomic force microscopic (AFM), and profilometry. The electrocatalytic activities of electrode were measured using cyclic voltammetry (CV) analysis. The growth of cobalt sulfide structure was confirmed by XRD. Therefore, the optimum deposition time of cobalt sulfide thin film electrode at 10 min was exhibiting the higher electrocatalytic activity with cathodic current and surface roughness of -3.36 mA.cm-2 and 34 nm, respectively.

Properties of zinc tin oxide thin film by aerosol assisted chemical vapor deposition (AACVD)

This study focuses on the properties of ZTO which have been deposited by a low-cost method namely aerosol assisted chemical vapor deposition (AACVD). The precursors used in this method were zinc acetate dihidrate and tin chloride dihydrate for ZTO thin film deposition. Both precursors were mixed and stirred until fully dissolved before deposition. The ZTO was deposited on borosilicate glass substrate for the investigation of optical properties. The films deposited have passed the scotch tape adherence test. XRD revealed that the crystal ZTO is slightly in the form of perovskite structure but several deteriorations were also seen in the spectrum. The UV-Vis analysis showed high transmittance of ∼85% and the band gap was calculated to be 3.85 eV. The average thickness of the film is around 284 nm. The results showed that the ZTO thin films have been successfully deposited by the utilization of AACVD method.

Characterizations of natural dye from garcinia mangostana with graphene oxide (GO) as sensitizer in dye-sensitizer solar cells

Usage of natural product in improvement of dye-sensitized solar cell (DSSC) have been look upon in research field. There is numerous different type of nature product was used as natural dye but the performance of DSSC with natural dye are low efficiency compare to DSSC with Ruthenium (II) dye due to low anchoring strength between dye molecule with TiO2 surface. This paper is about an experiment DSSC device with sensitizer of Mangosteen with Graphene Oxide as catalyst. The highest device efficiency with graphene oxide (GO) concentration of 0.50 mg/ml obtained in this experiment is 0.40% with short-circuit current density (Jsc) = 1.00 mA/cm2, open circuit voltage (Voc) = 0.61 V and fill factor(FF) = 65.72%. It shows that GO helped to increase device performance by increase the ability of sensitizer absorbed onto TiO2 and adding more passageway for carriers movement between TiO2 surface and dye sensitizer.

Model development of monolithic tandem silicon-perovskite solar cell by SCAPS simulation

Organic-inorganic lead halide perovskites have significant role in the photovoltaic (PV) technology due to its high efficiency, lightweight and cost effectiveness especially methyl ammonium lead (II) iodide (MALI). The MALI can act as absorber layer which has a band gap of 1.5 eV which is compatible to be paired with silicon (Si) solar cell with energy gap of 1.124 eV as a tandem solar cell. This tandem approach is an refined solution to improve the efficiency of Si solar cell that has been stuck around 25 % for 15 years. This study focuses on the development of the device configuration model for Si-perovskite tandem solar cell by using SCAPS simulation. The thickness and dopant concentration of perovskite layer have affected the solar cell parameters performance. The efficiency result obtained from SCAPS simulation is 27.29 % for Si-perovskite tandem solar cell with an open circuit voltage of 0.8178 V, short circuit current 43.55 mA/cm2 and fill factor 76.61 %.