Uttam Kumawat | IIT Delhi (original) (raw)
Papers by Uttam Kumawat
Physics, Simulation, and Photonic Engineering of Photovoltaic Devices IX
Due to the high cost of conventional crystalline silicon solar cells, researchers have been attra... more Due to the high cost of conventional crystalline silicon solar cells, researchers have been attracted towards the development of thin-film Si solar cells, where a several hundred nanometers thick amorphous Si (a-Si) or microcrystalline Si (μc-Si) solar cell layer is deposited by plasma-enhanced chemical vapor deposition (PECVD). This paper presents the use of plasmonic nanostructures in μc-Si p-i-n junction thin-film solar cells to increase the absorption in a broad spectral range. Finite-difference time-domain (FDTD) simulation results demonstrate a broadband absorption enhancement in these solar cells due to plasmonic nanostructures. The enhancement in the absorption is attributed to the enhanced electromagnetic fields in the active layer due to the excitation of surface plasmon modes and photonic Bloch modes at multiple wavelengths. Moreover, the plasmonic nanostructures lead to a significant enhancement in the shortcircuit current density of the μc-Si thin-film solar cell.
2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), 2018
In this study, we present Indium-rich InGaN thin film solar cells containing a periodic array of ... more In this study, we present Indium-rich InGaN thin film solar cells containing a periodic array of various plasmonic and dielectric nanostructures such as Ag nanogratings (NGs), ITO nanogratings, and Ag nanodiscs (NDs). Finite-difference time-domain (FDTD) simulations were carried out for solar cells containing nanostructures on the back side and on the front side of the solar cells, and an improvement in the performance of the solar cells was compared for the different geometries of these nanostructures. FDTD simulation results demonstrate a broadband absorption enhancement in the active-medium after employing a combination of Ag nanodiscs and ITO nanogratings. The Ag NDs lead to an enhanced surface plasmon-based scattering of longer wavelengths of light, while the ITO NGs lead to enhanced scattering of shorter wavelengths of light. This leads to a significant enhancement in optical absorption in the active medium, as well as in the short circuit current density, $\mathrm{J}_{\text{s...
We present Indium-rich InGaN thin-film solar cells containing plasmonic and dielectric nanostruct... more We present Indium-rich InGaN thin-film solar cells containing plasmonic and dielectric nanostructures such as Ag and ITO nanopillars. Finite-difference time-domain (FDTD) simulations were carried out for solar cells containing these nanostructures on the back side and on the front side of the solar cells, and an improvement in the performance of the solar cells was compared for the different geometries and sizes of these nanostructures. In order to develop highefficiency InGaN solar cells, the indium content in the InGaN active layer needs to be increased in order to cover the large solar spectral range. Recently, several reports have demonstrated the growth of single-crystalline Indium-rich InGaN alloys without phase separation by controlling the growth temperature and the pressure. Our FDTD simulation results demonstrate that the Ag nanostructures on the back side of the solar cell lead to an enhanced surface plasmonbased scattering mostly for longer wavelengths of light including...
The current photovoltaic module market is dominated by silicon solar cells, whose development is ... more The current photovoltaic module market is dominated by silicon solar cells, whose development is limited by high costs of manufacturing processes. The search for easy low temperature fabrication techniques has spurred the development of solar cells based on organic semiconductor polymers. Recent studies have reported polymer based solar cells with comparable power conversion efficiencies to those of commercially available silicon solar cell modules. In the face of these advances, higher efficiencies are still desirable to better utilize the available solar energy for power generation. Organic semiconducting polymers have a high coefficient of absorption, but short carrier path lengths which necessitates the fabrication of thin layers for optimal power generation. The introduction of plasmonic effects in these organic solar cells leads to an increase in the optical path length of the incident light in the active layer, thereby increasing the short circuit current density. In this wor...
We present plasmonics-enhanced organic solar cells (OSCs) containing nanostructures of plasmonic ... more We present plasmonics-enhanced organic solar cells (OSCs) containing nanostructures of plasmonic metals in the hole transport layer extending to the active layer of the solar cell. Finite-difference time-domain (FDTD) modeling was employed to simulate the interaction of incident light with the plasmonic nanostructures, leading to a broadband absorption enhancement in the OSCs. We studied the effect of employing nanostructures of different sizes and materials on the absorption enhancement in the OSCs. In some OSCs, we demonstrate 32% increase in the short circuit current density due to the presence of plasmonic nanostructures.
2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), 2018
In this paper, we present organic solar cells (OSCs) containing plasmonic silver nanostructures i... more In this paper, we present organic solar cells (OSCs) containing plasmonic silver nanostructures in the active medium poly[[9-(l-octylnonyl)-9H-carbazole-2,7 -diyl]-2,5-thiophenediyl-2, 1,3-benzothiadiazole-4,7 -diyl-2,5-thiophenediyl] (PCDTBT):[6], [6]-phenyl C71 butyric acid methyl ester (PC71BM). Finite-difference time-domain (FDTD) modeling was employed to simulate the interaction of incident light with plasmonic nanostructures of different shapes, leading to a broadband absorption enhancement in the OSCs. It is demonstrated that this enhancement is primarily due to enhanced far field scattering - localized surface plasmon excitation - from the nanostructures in the active medium. We demonstrate a 25.28% increase in the short circuit current density, mathrmJtextSC\mathrm{J}_{\text{SC}}mathrmJtextSC for the OSCs containing hexagonal nanodiscs in the active medium.
Energy Science & Engineering
Journal of the Optical Society of America B
Energy Science & Engineering
Solar cells of ternary alloys such as indium gallium nitride (InGaN) are attracting interest due ... more Solar cells of ternary alloys such as indium gallium nitride (InGaN) are attracting interest due to the tunable direct band gap energy of InGaN covering the whole solar spectrum ranging from 0.7 eV (band gap energy of InN) to 3.4 eV (band gap energy of GaN), 1,2 as well as superior photovoltaic characteristics of InGaN including high absorption coefficients (~10 5 cm −1) 3 and high carrier mobility. 1 Moreover, high stability (thermal and chemical) and superior radiation resistance of InGaN alloys allow operation of InGaN-based devices in extreme conditions such as space and terrestrial applications. 1,4 InGaN-based solar cells have been successfully fabricated with low indium contents of the InGaN alloy. 5-7 Lower indium content in InGaN leads to an increase in the band gap energy of InGaN, which in turn results in
Journal of the Optical Society of America B
Physics, Simulation, and Photonic Engineering of Photovoltaic Devices IX
Due to the high cost of conventional crystalline silicon solar cells, researchers have been attra... more Due to the high cost of conventional crystalline silicon solar cells, researchers have been attracted towards the development of thin-film Si solar cells, where a several hundred nanometers thick amorphous Si (a-Si) or microcrystalline Si (μc-Si) solar cell layer is deposited by plasma-enhanced chemical vapor deposition (PECVD). This paper presents the use of plasmonic nanostructures in μc-Si p-i-n junction thin-film solar cells to increase the absorption in a broad spectral range. Finite-difference time-domain (FDTD) simulation results demonstrate a broadband absorption enhancement in these solar cells due to plasmonic nanostructures. The enhancement in the absorption is attributed to the enhanced electromagnetic fields in the active layer due to the excitation of surface plasmon modes and photonic Bloch modes at multiple wavelengths. Moreover, the plasmonic nanostructures lead to a significant enhancement in the shortcircuit current density of the μc-Si thin-film solar cell.
2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), 2018
In this study, we present Indium-rich InGaN thin film solar cells containing a periodic array of ... more In this study, we present Indium-rich InGaN thin film solar cells containing a periodic array of various plasmonic and dielectric nanostructures such as Ag nanogratings (NGs), ITO nanogratings, and Ag nanodiscs (NDs). Finite-difference time-domain (FDTD) simulations were carried out for solar cells containing nanostructures on the back side and on the front side of the solar cells, and an improvement in the performance of the solar cells was compared for the different geometries of these nanostructures. FDTD simulation results demonstrate a broadband absorption enhancement in the active-medium after employing a combination of Ag nanodiscs and ITO nanogratings. The Ag NDs lead to an enhanced surface plasmon-based scattering of longer wavelengths of light, while the ITO NGs lead to enhanced scattering of shorter wavelengths of light. This leads to a significant enhancement in optical absorption in the active medium, as well as in the short circuit current density, $\mathrm{J}_{\text{s...
We present Indium-rich InGaN thin-film solar cells containing plasmonic and dielectric nanostruct... more We present Indium-rich InGaN thin-film solar cells containing plasmonic and dielectric nanostructures such as Ag and ITO nanopillars. Finite-difference time-domain (FDTD) simulations were carried out for solar cells containing these nanostructures on the back side and on the front side of the solar cells, and an improvement in the performance of the solar cells was compared for the different geometries and sizes of these nanostructures. In order to develop highefficiency InGaN solar cells, the indium content in the InGaN active layer needs to be increased in order to cover the large solar spectral range. Recently, several reports have demonstrated the growth of single-crystalline Indium-rich InGaN alloys without phase separation by controlling the growth temperature and the pressure. Our FDTD simulation results demonstrate that the Ag nanostructures on the back side of the solar cell lead to an enhanced surface plasmonbased scattering mostly for longer wavelengths of light including...
The current photovoltaic module market is dominated by silicon solar cells, whose development is ... more The current photovoltaic module market is dominated by silicon solar cells, whose development is limited by high costs of manufacturing processes. The search for easy low temperature fabrication techniques has spurred the development of solar cells based on organic semiconductor polymers. Recent studies have reported polymer based solar cells with comparable power conversion efficiencies to those of commercially available silicon solar cell modules. In the face of these advances, higher efficiencies are still desirable to better utilize the available solar energy for power generation. Organic semiconducting polymers have a high coefficient of absorption, but short carrier path lengths which necessitates the fabrication of thin layers for optimal power generation. The introduction of plasmonic effects in these organic solar cells leads to an increase in the optical path length of the incident light in the active layer, thereby increasing the short circuit current density. In this wor...
We present plasmonics-enhanced organic solar cells (OSCs) containing nanostructures of plasmonic ... more We present plasmonics-enhanced organic solar cells (OSCs) containing nanostructures of plasmonic metals in the hole transport layer extending to the active layer of the solar cell. Finite-difference time-domain (FDTD) modeling was employed to simulate the interaction of incident light with the plasmonic nanostructures, leading to a broadband absorption enhancement in the OSCs. We studied the effect of employing nanostructures of different sizes and materials on the absorption enhancement in the OSCs. In some OSCs, we demonstrate 32% increase in the short circuit current density due to the presence of plasmonic nanostructures.
2018 IEEE 18th International Conference on Nanotechnology (IEEE-NANO), 2018
In this paper, we present organic solar cells (OSCs) containing plasmonic silver nanostructures i... more In this paper, we present organic solar cells (OSCs) containing plasmonic silver nanostructures in the active medium poly[[9-(l-octylnonyl)-9H-carbazole-2,7 -diyl]-2,5-thiophenediyl-2, 1,3-benzothiadiazole-4,7 -diyl-2,5-thiophenediyl] (PCDTBT):[6], [6]-phenyl C71 butyric acid methyl ester (PC71BM). Finite-difference time-domain (FDTD) modeling was employed to simulate the interaction of incident light with plasmonic nanostructures of different shapes, leading to a broadband absorption enhancement in the OSCs. It is demonstrated that this enhancement is primarily due to enhanced far field scattering - localized surface plasmon excitation - from the nanostructures in the active medium. We demonstrate a 25.28% increase in the short circuit current density, mathrmJtextSC\mathrm{J}_{\text{SC}}mathrmJtextSC for the OSCs containing hexagonal nanodiscs in the active medium.
Energy Science & Engineering
Journal of the Optical Society of America B
Energy Science & Engineering
Solar cells of ternary alloys such as indium gallium nitride (InGaN) are attracting interest due ... more Solar cells of ternary alloys such as indium gallium nitride (InGaN) are attracting interest due to the tunable direct band gap energy of InGaN covering the whole solar spectrum ranging from 0.7 eV (band gap energy of InN) to 3.4 eV (band gap energy of GaN), 1,2 as well as superior photovoltaic characteristics of InGaN including high absorption coefficients (~10 5 cm −1) 3 and high carrier mobility. 1 Moreover, high stability (thermal and chemical) and superior radiation resistance of InGaN alloys allow operation of InGaN-based devices in extreme conditions such as space and terrestrial applications. 1,4 InGaN-based solar cells have been successfully fabricated with low indium contents of the InGaN alloy. 5-7 Lower indium content in InGaN leads to an increase in the band gap energy of InGaN, which in turn results in
Journal of the Optical Society of America B