Swapan Kumar Datta | Indian Institute of Engineering Science and Technology, Shibpur (original) (raw)
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University of Canterbury/Te Whare Wānanga o Waitaha
Sardar Vallabhbhai Patel National Institute of Technology Surat
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Papers by Swapan Kumar Datta
The effect of embedding nanoentities (silica and voids) on the optical and electrical performance... more The effect of embedding nanoentities (silica and voids) on the optical and electrical performance of Si solar cells has been investigated in an attempt to decouple the Anti-Reflection (AR) properties of the standard nitride coated Solar Cells (SCs) and the scattering properties of the nanoentities. The decoupling will ensure the use of the scattering properties of the nanoentities without disturbing the optimized reflection characteristics of a standard SC. Lumerical V R Finite Difference Time Domain Solutions software has been used to simulate the optical performance of solar cells after embedding nanoentities in the emitter region. Simulation results indicate that total decoupling of the AR properties and the scattering properties of the nanoentities is not obtained. Electrical performance evaluation of the system reveals a substantial relative improvement (1.7%) in the efficiency of thick (200 lm) SCs which further increases for thin (2 lm) film cells (23%) when 100 nm radius nanovoids having 30% area coverage are embedded at a depth of 200 nm from the silicon surface. The relative improvement is compromised if the changes in the material parameters due to embedding nanoentities are taken in to account. V C 2013 AIP Publishing LLC. [http://dx.
The suitability of using spherical metal and dielectric nanoparticles on the top of a silicon sol... more The suitability of using spherical metal and dielectric nanoparticles on the top of a silicon solar cell has been investigated. An enhancement index factor (EIF) for each wavelength of light and an averaged EIF for the AM 1.5 solar spectrum, weighted by the photon flux, has been introduced. These factors estimate the effect of the nanoparticles in improving the performance of the solar cells, considering the absorption loss due to joule heating, fraction of radiation scattered into the substrate and the front scattered radiation pattern. A systematic comparison between silver and dielectric nanoparticles (silica, silicon nitride, titanium dioxide) shows that titanium dioxide and silicon nitride nano particles of sizes !100 nm exhibit larger enhancements compared to that of silver nanoparticles of similar sizes. Further, as the dielectric constant of the dielectric nanoparticles increases, the optimal particle size corresponding to maximal enhancement shifts towards lower value. At optimal particle sizes, the enhancement is 1.5-2 times greater than that due to silver nanoparticles.
Use of lossless nanoentities (dielectric nanoparticles/voids) atop and embedded in a silicon subs... more Use of lossless nanoentities (dielectric nanoparticles/voids) atop and embedded in a silicon substrate has been investigated for obtaining high efficiency silicon solar cells. Dielectric nanoparticles atop silicon help in grading the refractive index mismatch between single antireflection layer coated silicon and air, maximizing the photon injection. Thereafter, nanoentities embedded inside the silicon enhance the absorption of these injected photons by large angular scattering resulting in light trapping. Design guidelines are laid down for maximized injection and enhanced absorption of the incident photons. Optical simulations are carried out using Lumerical FDTD Solutions R . Results of optical simulations are mapped onto the electrical model of a solar cell considering the changes in electrical properties of the emitter layer by embedded nanoentities to estimate the efficiency of the solar cell. It is seen that a relative improvement in efficiency of about 6% is obtained when 200 nm radius voids having 30% coverage are embedded in a 20 µm thick solar cell, with an antireflection coating of 60 nm thick titania bottom layer, and 50 nm radius silicon nitride nanoparticles having 78% coverage as the top layer. This improvement in efficiency is attributed to the enhanced quantum efficiency, which is found to be pronounced in thinner cells (25% for a thin cell 2 µm thick).
Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar... more Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar cells (SCs) has been applied using highly monodispersed and stable silica nanoparticles (NPs). The silica NPs having 300 nm diameter were synthesized by Stober technique where the size of the NPs was controlled by varying the alcohol medium. The synthesized silica NPs were analysed by dynamic light scattering technique and Fourier transform infrared spectroscopy. The NPs were spin coated on glass side of fluorinated tin oxide (SnO 2 : F) coated glass superstrate and optimization of the concentration of the colloidal solution, spin speed and number of coated layers was done to achieve minimum reflection characteristics. An estimation of the distribution of the NPs for different optimization parameters has been done using field-emission scanning electron microscopy. Subsequently, the transparent conducting oxide coated glass with the layer having the minimum reflectance is used for fabrication of amorphous silicon SC. Electrical analysis of the fabricated cell indicates an improvement of 6.5% in short-circuit current density from a reference of 12.40 mA cm −2 while the open circuit voltage and the fill factor remains unaltered. A realistic optical model has also been proposed to gain an insight into the system.
The effect of embedding nanoentities (silica and voids) on the optical and electrical performance... more The effect of embedding nanoentities (silica and voids) on the optical and electrical performance of Si solar cells has been investigated in an attempt to decouple the Anti-Reflection (AR) properties of the standard nitride coated Solar Cells (SCs) and the scattering properties of the nanoentities. The decoupling will ensure the use of the scattering properties of the nanoentities without disturbing the optimized reflection characteristics of a standard SC. Lumerical V R Finite Difference Time Domain Solutions software has been used to simulate the optical performance of solar cells after embedding nanoentities in the emitter region. Simulation results indicate that total decoupling of the AR properties and the scattering properties of the nanoentities is not obtained. Electrical performance evaluation of the system reveals a substantial relative improvement (1.7%) in the efficiency of thick (200 lm) SCs which further increases for thin (2 lm) film cells (23%) when 100 nm radius nanovoids having 30% area coverage are embedded at a depth of 200 nm from the silicon surface. The relative improvement is compromised if the changes in the material parameters due to embedding nanoentities are taken in to account. V C 2013 AIP Publishing LLC. [http://dx.
The suitability of using spherical metal and dielectric nanoparticles on the top of a silicon sol... more The suitability of using spherical metal and dielectric nanoparticles on the top of a silicon solar cell has been investigated. An enhancement index factor (EIF) for each wavelength of light and an averaged EIF for the AM 1.5 solar spectrum, weighted by the photon flux, has been introduced. These factors estimate the effect of the nanoparticles in improving the performance of the solar cells, considering the absorption loss due to joule heating, fraction of radiation scattered into the substrate and the front scattered radiation pattern. A systematic comparison between silver and dielectric nanoparticles (silica, silicon nitride, titanium dioxide) shows that titanium dioxide and silicon nitride nano particles of sizes !100 nm exhibit larger enhancements compared to that of silver nanoparticles of similar sizes. Further, as the dielectric constant of the dielectric nanoparticles increases, the optimal particle size corresponding to maximal enhancement shifts towards lower value. At optimal particle sizes, the enhancement is 1.5-2 times greater than that due to silver nanoparticles.
Use of lossless nanoentities (dielectric nanoparticles/voids) atop and embedded in a silicon subs... more Use of lossless nanoentities (dielectric nanoparticles/voids) atop and embedded in a silicon substrate has been investigated for obtaining high efficiency silicon solar cells. Dielectric nanoparticles atop silicon help in grading the refractive index mismatch between single antireflection layer coated silicon and air, maximizing the photon injection. Thereafter, nanoentities embedded inside the silicon enhance the absorption of these injected photons by large angular scattering resulting in light trapping. Design guidelines are laid down for maximized injection and enhanced absorption of the incident photons. Optical simulations are carried out using Lumerical FDTD Solutions R . Results of optical simulations are mapped onto the electrical model of a solar cell considering the changes in electrical properties of the emitter layer by embedded nanoentities to estimate the efficiency of the solar cell. It is seen that a relative improvement in efficiency of about 6% is obtained when 200 nm radius voids having 30% coverage are embedded in a 20 µm thick solar cell, with an antireflection coating of 60 nm thick titania bottom layer, and 50 nm radius silicon nitride nanoparticles having 78% coverage as the top layer. This improvement in efficiency is attributed to the enhanced quantum efficiency, which is found to be pronounced in thinner cells (25% for a thin cell 2 µm thick).
Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar... more Antireflective coating on front glass of superstrate-type single junction amorphous silicon solar cells (SCs) has been applied using highly monodispersed and stable silica nanoparticles (NPs). The silica NPs having 300 nm diameter were synthesized by Stober technique where the size of the NPs was controlled by varying the alcohol medium. The synthesized silica NPs were analysed by dynamic light scattering technique and Fourier transform infrared spectroscopy. The NPs were spin coated on glass side of fluorinated tin oxide (SnO 2 : F) coated glass superstrate and optimization of the concentration of the colloidal solution, spin speed and number of coated layers was done to achieve minimum reflection characteristics. An estimation of the distribution of the NPs for different optimization parameters has been done using field-emission scanning electron microscopy. Subsequently, the transparent conducting oxide coated glass with the layer having the minimum reflectance is used for fabrication of amorphous silicon SC. Electrical analysis of the fabricated cell indicates an improvement of 6.5% in short-circuit current density from a reference of 12.40 mA cm −2 while the open circuit voltage and the fill factor remains unaltered. A realistic optical model has also been proposed to gain an insight into the system.