M.Y. Sulaiman

Effect of CdCl2 treatment on physical properties of CdTe films with different compositions fabricated by chemical molecular beam deposition

CdTe films with different compositions (Cd-rich, Te-rich and stoichiometric) were fabricated by revolutionary novel and low cost chemical molecular beam deposition (CMBD) method in the atmospheric pressure hydrogen flow. Cd and Te granules were used as precursors. The films were deposited on ceramic (SiO2: Al2O3) substrates at 600°C. The growth rate was varied in the range of 20–30 Å/s. The composition of the samples was changed by controlling the molecular beam intensity (MBI) ratio Cd/Te. Effect of CdCl2 treatment on morphology, photoluminescence and electrical properties of CdTe films was investigated by AFM, Raman, photoluminescence (PL) and Hall methods.

Effect of the composition on physical properties of CdTe absorber layer fabricated by chemical molecular beam deposition for use in thin film solar cells

We developed revolutionary novel and low cost and nonvacuum chemical molecular beam deposition method for fabrication of thin film II-VI solar cells in the atmospheric pressure gas (He, Ar, H2) flow. High quality polycrystalline CdTe films with different compositions (stoichiometric and Cd/Te ≤1.0 and Cd/Te ≥ 1.0) and thickness of 2–3 μm were fabricated on ceramic (SiO2:Al2O3) substrates at temperature of 600 °C. Separate sources of Cd and Te with respective purities of 99.999% were used as precursors. The growth rate was varied in the range of 9–30 A/s. The effect of the composition and CdCl2 treatment on the structure, intrinsic point defects, and electrical properties of CdTe films was investigated by XRD, AFM, Raman spectra, photoluminescence, and Hall methods.

Revolutionary novel and low cost CMBD method for fabrication of CdTe absorber layer for use in thin film solar cells

Abstract We developed revolutionary novel and low cost and non-vacuum chemical molecular beam deposition method for fabrication of thin film II–VI solar cells in the atmospheric pressure gas (He, Ar and H2) flow. High quality polycrystalline CdTe films with different compositions (stoichiometric and Cd/Te ⩽1·0 and Cd/Te ⩾1·0) and thickness of 2–3 μm were fabricated on ceramic (SiO2–Al2O3) substrates at a temperature of 600°C. Separate sources of Cd and Te with respective purities of 99·999% were used as precursors. The growth rate was varied in the range of 9–30 Å s−1. The effects of the composition and CdCl2 treatment on the structure, intrinsic point defects and electrical properties of CdTe films were investigated by X-ray diffraction, atomic force microscopy, Raman spectra, photoluminescence and Hall methods.

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.

Design and Modeling of One Refrigeration Ton Solar Assisted Adsorption Air Conditioning System

The modeling of the performance of a one refrigeration ton (RT) solar assisted adsorp-tion air-conditioning refrigeration system using activated carbon fiber/ethanol as theadsorbent/adsorbate pair has been undertaken in this study. The effects of hot water,cooling water, chilled water inlet temperatures, and hot water and chilled water flowrates were taken into consideration in the optimization of the system and in the design ofthe condenser, evaporator, and hot water storage tank. The study includes analysis of theweather data and its effect on both the adsorption system and the cooling load. This isthen followed by estimation of the cooling capacity and coefficient of performance (COP)of the adsorption system as a function of the input parameters. The results of the modelwill be compared to experimental data in a next step. [DOI: 10.1115/1.4027964]Keywords: solar energy, adsorption air conditioning, activated carbon fiber/ethanol,cooling load

Review of Polymer, Dye-Sensitized, and Hybrid Solar Cells

The combination of inorganic nanoparticles semiconductor, conjugated polymer, and dye-sensitized in a layer of solar cell is now recognized as potential application in developing flexible, large area, and low cost photovoltaic devices. Several conjugated low bandgap polymers, dyes, and underlayer materials based on the previous studies are quoted in this paper, which can provide guidelines in designing low cost photovoltaic solar cells. All of these materials are designed to help harvest more sunlight in a wider range of the solar spectrum besides enhancing the rate of charge transfer in a device structure. This review focuses on developing solid-state dye-synthesized, polymer, and hybrid solar cells.

Fabrication and characterization of Al-BSF bifacial solar cell

Crystalline silicon, in its single crystalline or multi-crystalline (mc) format, dominates the photovoltaic (PV) industry. However, PV energy generation cost is still higher than energy-conversion costs of carbon-based fossil fuels. Since the price of silicon wafer accounts for almost 50% of the energy conversion cost, historically cost reduction through reducing Si wafer thickness has been successful approach. This approach is now reaching its limits due to yield reduction of thinner wafers, thermal expansion mismatch between Al and thin Si wafer, and reduced optical absorption. In recent years, bifacial solar cells have attracted attention due to their several attractive features including: (a) applicability to thinner wafers, (b) superior high temperature performance, (c) elimination of wafer warpage, (d) lower metal usage, (e) symmetric structure irrespective of n or p wafer, (f) enhanced power generation, and (g) simple processing. A bifacial solar cell structure consists of bulk (p or n-type semiconductor), emitter, back surface field (BSF), anti reflective coatings (ARC) and identical metal grids on both sides. In this study, a new combination method of emitter and BSF layer for npp+ bifacial structure has been investigated. The npp+ structure has been chosen due to its inherent simplicity and process similarity to industrial monofacial solar cell manufacturing. The new process relies on POCl3 diffusion for emitter formation on the front side; and screen printed Aluminum (Al) for BSF on the rear surface. A screen-printed process is used to apply Al to the wafer followed by high temperature firing process to form Al back surface field and contact. In this case, excess Al is removed from the rear using wet-chemical etching resulting in an Al-doped p+ surface. LIV, surface photovoltage, and EDAX techniques were employed to characterized solar cell performance; PC1D simulations were applied to determine front and rear surface efficiencies. Poor rear surface performance of such bifacial solar cells has been attributed to inadequate passivation, higher reflection, and ineffective back surface field.

Silicon Nitride Passivation of Silicon Nanowires Solar Cell

Vertical aligned silicon nanowires were synthesized using chemical etching of silicon wafer. Influence of a silicon nitride layer on the top of the silicon nanowires solar cell has been investigated. The optical properties of a Si NWs array with and without silicon nitride passivation layer are examined in terms of optical reflection property. In the presence of silicon nitride layer, 1% reflection ratio in the spectral range (250-1000nm) is achieved. In addition, the solar cell characteristics have been significantly improved, which exhibits high short circuit current as well high efficiency. Based on the current-voltage measurements and morphology results, we show that the silicon nitride layer can passivate the defects generated by wet etching processes.

Investigation of back surface fields effect on bifacial solar cells

A bifacial solar cell, in contrast with a conventional monofacial solar cell, produces photo-generated current from both front and back sides. Bifacial solar cell is an attractive candidate for enhancing photovoltaic (PV) market competitiveness as well as supporting the current efforts to increase efficiency and lower material costs. This paper reports on the fabrication of bifacial solar cells using phosphorus-oxytrichloride (POCl3) emitter formation on p-type, nanotextured silicon (Si) wafer. Backside surface field was formed through Al-diffusion using conventional screen-printing process. Bifacial solar cells with a structure of n+pp+ with and without back surface field (BSF) were fabricated in which silicon nitride (SiN) anti reflection and passivation films were coated on both sides, followed by screen printing of Argentum (Ag) and Argentum/Aluminum (Ag/Al) on front and back contacts, respectively. Bifacial solar cells without BSF exhibited open circuit voltage (VOC) of 535 mV for front and 480 mV fo...

Case study of wind-induced natural ventilation tower in hot and humid climatic conditions

This paper investigates the performance of a wind-induced natural ventilation tower through an empirical analysis in hot and humid climatic conditions. There are mainly two methods for inducing natural ventilation; namely stack ventilation and wind-induced ventilation. Due to the relatively lower difference between the indoor and outdoor temperature in hot and humid conditions, stack ventilation method alone is rendered insufficient to create desirable air flow between outdoor and indoor building environment to achieve comfort and indoor air quality for the building occupant. Hence, wind-induced ventilation method can be used to achieve the desired air flow rates and improve the indoor air quality for the building. This study revealed that at external wind speed of 0.1m/s, the aerodynamic inverted airfoil roof geometry on the wind-induced natural ventilation tower is able to generate extraction air flow rate of 10,000m3/h with average of 57 ACH to provide comfort and indoor air quality to the internal building environment in hot and humid climatic conditions.