Senthilarasu Sundaram

The Application of Graphene and Its Derivatives to Energy Conversion, Storage, and Environmental and Biosensing Devices

Graphene (GR) and its derivatives are promising materials on the horizon of nanotechnology and material science and have attracted a tremendous amount of research interest in recent years. The unique atom-thick 2D structure with sp(2) hybridization and large specific surface area, high thermal conductivity, superior electron mobility, and chemical stability have made GR and its derivatives extremely attractive components for composite materials for solar energy conversion, energy storage, environmental purification, and biosensor applications. This review gives a brief introduction of GRs unique structure, band structure engineering, physical and chemical properties, and recent energy-related progress of GR-based materials in the fields of energy conversion (e.g., photocatalysis, photoelectrochemical water splitting, CO2 reduction, dye-sensitized and organic solar cells, and photosensitizers in photovoltaic devices) and energy storage (batteries, fuel cells, and supercapacitors). The vast coverage of advancements in environmental applications of GR-based materials for photocatalytic degradation of organic pollutants, gas sensing, and removal of heavy-metal ions is presented. Additionally, the use of graphene composites in the biosensing field is discussed. We conclude the review with remarks on the challenges, prospects, and further development of GR-based materials in the exciting fields of energy, environment, and bioscience.

Natural dye sensitized TiO2 nanorods assembly of broccoli shape based solar cells

TiO2 nanorods based thin films with rutile phase have been synthesized using template free low temperature hydrothermal method. The scanning electron microscope images showed that the prepared TiO2 samples were made of TiO2 nanorods and the nanorods had arranged by itself to form a broccoli like shape. The X-ray diffraction studies revealed that the prepared TiO2 samples exhibit rutile phase. The grown TiO2 nanorods had been sensitized using the flowers of Sesbania (S) grandiflora, leaves of Camellia (C) sinensis and roots of Rubia (R) tinctorum. Dye sensitized solar cells had been fabricated using the natural dye sensitized TiO2 nanorods based thin film photoelectrode and the open circuit voltage and short circuit current density were found to lie in the range of 0.45-0.6 V and 5.6-6.4 mA/cm(2) respectively. The photovoltaic performance of all the fabricated natural dye sensitized TiO2 solar cells indicate that natural dyes have the potential to be used as effective sensitizer in dye sensitized solar cells.

Effect of Spectral Irradiance Variations on the Performance of Highly Efficient Environment-Friendly Solar Cells

The increasing environmental concerns on photovoltaic (PV) materials have attracted much attention to environment-friendly materials for solar energy conversion. In this paper, the environment-friendly materials based on dye-sensitized solar cells (DSSC), CuZnSnSSe2 (CZTS), and CH3NH3SnI3 based on perovskite solar cells have been studied for their spectral dependence at selected different locations with varying parameters such as air mass, aerosol optical depth, and precipitable water. The spectral dependences of the materials have been obtained by the use of the spectral factor, and ground-based long-term climatologies in conjunction with the Simple Model of the Atmospheric Radiative Transfer of Sunshine have been used. Results show that the perovskite and DSSC solar cells show an important spectral dependence with annual spectral gains up to 3% and spectral losses up to -15%. On the other hand, CZTS solar cells show a low spectral dependence with annual spectral gains up to 2% and spectral losses up to -4%.

Multiple Phase Change Material (PCM) Configuration for PCM-Based Heat Sinks—An Experimental Study

A small-scale phase change material (PCM)-based heat sink can regulate the temperature of electronics due to high latent-heat capacity. Three different heat sinks are examined to study the effects of PCM combination, arrangement of PCMs in multiple-PCM heat sink, PCM thickness, melting temperature and intensity of heat source on the thermal behavior of heat sink. Results are obtained for the temperature distribution across the heat sink and the PCM melting profile. It is concluded that (i) PCM combination RT50–RT55 increases the thermal regulation period and also reduces the heat sink temperature at the end of the operation, (ii) the RT58–RT47 arrangement slightly reduces the maximum temperature as compared to RT47–RT58, (iii) As PCM thickness increases from 30 mm to 60 mm, the thermal-regulation-period increases by 50 min, (iv) As the PCM melting temperature increases, the thermal-regulation-period and the heat sink temperature increase and (v) The thermal-regulation-period decreases as the power rating increases from 1 to 2 W.

Photovoltaics Fundamentals, Technology and Application

Robert McConnell National Renewable Energy Laboratory 23.1 Photovoltaics ..................................................................... 23-

Thermal analysis of a multi-layer microchannel heat sink for cooling concentrator photovoltaic (CPV) cells

Concentrator Photovoltaic (CPV) technology is increasingly being considered as an alternative option for solar electricity generation. However, increasing the light concentration ratio could decrease the system output power due to the increase in the temperature of the cells. The performance of a multi-layer microchannel heat sink configuration was evaluated using numerical analysis. In this analysis, three dimensional incompressible laminar steady flow model was solved numerically. An electrical and thermal solar cell model was coupled for solar cell temperature and efficiency calculations. Thermal resistance, solar cell temperature and pumping power were used for the system efficiency evaluation. An increase in the number of microchannel layers exhibited the best overall performance in terms of the thermal resistance, solar cell temperature uniformity and pressure drop. The channel height and width has no effect on the solar cell maximum temperature. However, increasing channel height leads to a reducti...

Thermal regulation of building-integrated concentrating photovoltaic system using phase change material

Thermal regulation of building-integrated concentrating photovoltaic (BICPV) systems have a direct influence on the photovoltaic performance. This paper investigates the thermal behavior of a BICPV and phase change material (PCM) system through numerical modeling simulations. Based on an updated mathematical model, theoretical simulation has been conducted for a BICPV-PCM system. The results show a 3% electrical efficiency improvement of the BICPV-PCM system in certain cases.

Electricity enhancement and thermal energy production from concentrated photovoltaic integrated with a 3-layered stacked micro-channel heat sink

The thermal effectiveness of three types of heat sink hsssas been investigated experimentally using a flexible kapton heater to simulate the generated heat from a CPV system for various heating loads. The three heat sinks are an air cooled flat aluminum heat sink, an air cooled finned aluminum heat sink and a water cooled 3-layered stacked micro-channel heat sink. It is shown that the temperature of the heater surface is reduced dramatically by using the finned heat sink compared to the flat plate heat sink. Also, the 3-layered stacked micro-channel heat sink is able to reduce the heater surface temperature below 50°C for 5.5W heater power. The work also studies numerically the effect of the 3-layered stacked micro-channel heat sink in a single solar cell receiver for a 500× concentration in enhancing the solar cell electrical efficiency and production of the thermal energy. The study uses a three dimensional modelling approach for real weather conditions. The results show a high solar cell electricity performance.The thermal effectiveness of three types of heat sink hsssas been investigated experimentally using a flexible kapton heater to simulate the generated heat from a CPV system for various heating loads. The three heat sinks are an air cooled flat aluminum heat sink, an air cooled finned aluminum heat sink and a water cooled 3-layered stacked micro-channel heat sink. It is shown that the temperature of the heater surface is reduced dramatically by using the finned heat sink compared to the flat plate heat sink. Also, the 3-layered stacked micro-channel heat sink is able to reduce the heater surface temperature below 50°C for 5.5W heater power. The work also studies numerically the effect of the 3-layered stacked micro-channel heat sink in a single solar cell receiver for a 500× concentration in enhancing the solar cell electrical efficiency and production of the thermal energy. The study uses a three dimensional modelling approach for real weather conditions. The results show a high solar cell electricity pe...

Thin Film Photovoltaics

Abstract Thin film solar cell technology has recently seen some radical advancement as a result of new materials and innovations in device structures. The increase in the efficiency of thin film solar cells and perovskite into 23% mark has created significant attention in the photovoltaic market, particularly in the integrated photovoltaic (BIPV) field. The efficiency increase in perovskite solar cells has significantly increased the potential thin film PVs, to become a low cost alternative for commercially available solar cell technologies. However, the main challenges for thin film technologies, including perovskite solar cells, are their stability and toxicity involved in the manufacturing process. An attempt has been made to report on the developments into thin film materials and the efficiencies achieved. Key deposition and growth techniques and challenges are also reported in this chapter.

A review on applications of Cu2ZnSnS4 as alternative counter electrodes in dye-sensitized solar cells

A contribution of counter electrode (CE) emphasis a great impact towards enhancement of a dye-sensitized solar cells (DSSC) performance and Pt based CE sets a significant benchmark in this field. Owing to cost effective noble metal, less abundance and industrial large scale application purpose, an effective replacement for Pt is highly demanded. There are several approaches to improve the performance of a CE for enhancing the power conversion efficiency with a less costly and facile device. To address this issue, reasonable efforts execute to find out suitable replacement of Pt is becoming a challenge by keeping the same electrochemical properties of Pt in a cheaper and eco-friendlier manner. With this, cheaper element based quaternary chalcogenide, Cu2ZnSnS4 (CZTS) becomes a prominent alternative to Pt and used as a successful CE in DSSC also. This review presents brief discussion about the basic properties of CZTS including its synthesis strategy, physicochemical properties and morphology execution and ultimate application as an alternative Pt free CE for a low cost based enhanced DSSC device. It is therefore, imperative for engineering of CZTS material and optimization of the fabrication method for the improvement of DSSC performance.A contribution of counter electrode (CE) emphasis a great impact towards enhancement of a dye-sensitized solar cells (DSSC) performance and Pt based CE sets a significant benchmark in this field. Owing to cost effective noble metal, less abundance and industrial large scale application purpose, an effective replacement for Pt is highly demanded. There are several approaches to improve the performance of a CE for enhancing the power conversion efficiency with a less costly and facile device. To address this issue, reasonable efforts execute to find out suitable replacement of Pt is becoming a challenge by keeping the same electrochemical properties of Pt in a cheaper and eco-friendlier manner. With this, cheaper element based quaternary chalcogenide, Cu2ZnSnS4 (CZTS) becomes a prominent alternative to Pt and used as a successful CE in DSSC also. This review presents brief discussion about the basic properties of CZTS including its synthesis strategy, physicochemical properties and morphology execution and...