Energy Materials & Technology
Shivendra Pratap Ray; Sadanand .; Pooja Lohia; D. K. Dwivedi
Abstract
Due to the versatility, non-toxicity and earth abundancy of raw material, SnS has considered a very useful semiconductor material and the harvesting of photovoltaic energy from this kind of semiconductor material is comparatively easier than others since it is highly efficient and cost-effective. The ...
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Due to the versatility, non-toxicity and earth abundancy of raw material, SnS has considered a very useful semiconductor material and the harvesting of photovoltaic energy from this kind of semiconductor material is comparatively easier than others since it is highly efficient and cost-effective. The simulation of a unique combination of device structure (ITO/SnO2/SnS/NiO/Mo) has been done and found to be worthful. Past work is quite good but unable to achieve the standard of enhanced open-circuit voltage along with the power conversing efficiency as well. The use of Hole Transport Layer (HTL) has been remarkable too since surface recombination has fallen sharply. The PCE hiked by 25% to 27.62% regardless of it is practically unattainable but in reality, it will prove as a milestone in this area if and only if we are using HTL as well. The different HTL layer has been studied for the proposed device structure and elaborated well. For the benefit of mankind, it is completely low cost and useable along with quite good performance.
Shuo-En Wu; Ya-Ping Hsieh
Abstract
Graphene’s high carrier mobility and ambipolar nature has the potential to improve electronic devices. The absence of a band-gap necessitates heterostructure devices. Schottky-barrier devices consisting of an interface between graphene and a semiconductor represent the simplest heterostructure. ...
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Graphene’s high carrier mobility and ambipolar nature has the potential to improve electronic devices. The absence of a band-gap necessitates heterostructure devices. Schottky-barrier devices consisting of an interface between graphene and a semiconductor represent the simplest heterostructure. Despite its simplicity, graphene-based Schottky barrier devices are not well understood and exhibit low injection efficiencies. We here investigate the impact of graphene/metal interaction on the properties of the Schottky-barrier. Besides the commonly employed Au/graphene we use Pt/graphene contacts. We find that the injection efficiency for Pt is 5x higher than for Au and systematically study the origin of this behavior. We identify a large difference in Richardson’s constant due to changes in the density of surface states. The demonstrated ability to increase the injection current was applied to improve the efficiency of graphene-based Schottky solar cells by 13x.
Abhinav Bhatnagar; Vijay Janyani
Abstract
Over the past few years thin film planar heterojunctions solar cells have made much progress as a low cost with high power conversion efficiency photovoltaic devices. Among the materials used in fabricating such solar cells organometal trihalide perovskite (MAPbI3) has proven to be a promising absorber ...
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Over the past few years thin film planar heterojunctions solar cells have made much progress as a low cost with high power conversion efficiency photovoltaic devices. Among the materials used in fabricating such solar cells organometal trihalide perovskite (MAPbI3) has proven to be a promising absorber material due to cheaper organic-inorganic perovskite compounds, abundantly available in nature, ease of fabrication and compatible with low temperature large scale processing. In addition to the efficient absorption in ultra-violet range the material possess intriguing optoelectronic properties such as high crystallinity, high carrier mobility and large carrier diffusion lengths. Currently, the highest power conversion efficiency achieved by such perovskite solar cells is only 23.9% as reported in 2017. In this work we demonstrate a thin film organometal trihalide perovskite solar cell with hybrid interfaces between different materials which are selected after extensive study to achieve reduced recombination and high performance. Further, the absorption of the incident solar spectrum is enhanced by incorporating a 1D photonic crystal at the bottom of the cell facilitating the photon recycling process. The proposed solar cell parameters are numerically computed using rigorous coupled wave algorithm through SYNOPSYS RSOFT CAD tool. The thickness of each layer of the structure is optimized using MOST scanning and optimization module of RSOFT CAD tool to achieve highest power conversion efficiency at minimum device thickness (~2 µm). The power conversion efficiency thus obtained is 25.2% with a fill factor of 86.3% at AM 1.5, which is very promising. This demonstrates the remarkable potential of the proposed design to achieve efficiencies over 20% and compete with the existing crystalline silicon photovoltaic market.
Marshall Wilson; Jie Cui;Jacek Lagowski; Alexandre Savtchouk; Ziv Hameiri
Abstract
This work demonstrates the effectiveness of non-contact Kelvin-probe and surface photovoltage characterization of the work function (WF) induced barriers formed in silicon (Si) by thin 5nm carrier selective contact films of MoOx, TiO2 and MgF2. The calibrated Kelvin probe in the dark and under ...
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This work demonstrates the effectiveness of non-contact Kelvin-probe and surface photovoltage characterization of the work function (WF) induced barriers formed in silicon (Si) by thin 5nm carrier selective contact films of MoOx, TiO2 and MgF2. The calibrated Kelvin probe in the dark and under strong illumination where used to determine the dark WF of the deposited films and the band bending in the Si, FBB = WFDark – WFLight. The ac-surface photo voltage provided an independent measurement of the Si depletion layer width. Whole wafer mapping of all parameters can be performed. For n-type Si the high work function oxides MoOx (WF~5.7eV) and TiO2 (WF~5.0eV) are found to induce a depletion barrier with the height increasing with WF as FBB[eV] = 0.23WF – 0.77, i.e. quite similar to the well-known relationship for metal-silicon contacts. For the low work function MgF2 film, a depletion barrier was induced only in p-type Si. For this case, full wafer mapping revealed a lower WF pattern coinciding with larger band bending giving the slope, DFBB/DWF ~ -0.52. The slopes of 0.23 and 0.52 for n- and p-type Si deviates significantly from the ideal slope of 1. This result implies that the barrier formation at the Film-Si heterojunction is limited by the effect of interfacial layers and interface states in analogy to the well-known effects in Metal-Si contacts. It is believed that this demonstrated very fast, preparation-free, non-contact characterization technique can benefit research and engineering of selective contacts for solar cells.
Illia Dobryden; Baligh Touati; Abdelaziz Gassoumi; Alberto Vomiero; Najoua Kamoun; Nils Almqvist
Abstract
Lead sulphide (PbS) is a direct band gap IV–VI intrinsic p-type semiconductor with good potential for application in solar cells, sensors, etc. Doping the films with Cu 2+ ions may improve the electrical properties. Here, Cu-doped PbS films were deposited on conducting glass substrates. The morphology, ...
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Lead sulphide (PbS) is a direct band gap IV–VI intrinsic p-type semiconductor with good potential for application in solar cells, sensors, etc. Doping the films with Cu 2+ ions may improve the electrical properties. Here, Cu-doped PbS films were deposited on conducting glass substrates. The morphology, topography and thickness of the doped PbS films were examined using atomic force microscopy (AFM) and high-resolution SEM. AFM analysis showed decreasing surface roughness and grain size with the increase of Cu 2+ concentration from 0.5 to 2.0 at%. Local surface electrical measurements using conducting AFM and Kelvin probe force microscopy showed the possibility to probe semi-quantitatively the changes in surface potential, work function, and Fermi level upon doping of the films. The estimated apparent work function for the un-doped PbS grains in the film was slightly above 4.5 eV, while it decreased to a minimum value of 4.43-4.45 eV at 1–1.5 at% Cu-doping. Conducting AFM measurements showed that local resistance of the doped samples is lower than on pure PbS films. These results indicate Cu doping as an effective strategy to tune the electrical properties of PbS thin films toward the development of suitable optically active materials for application in photovoltaics.
Geeta Saini; Vandna Luthra;R. P. Tandon; Vishal Sharma
Abstract
The synthesis and characterization of two novel 3-thienyl based polythiophene derivatives PT and BT have been presented. These polymers have been synthesized by convenient and ecofriendly Pd catalyzed direct arylation polymerization method. In these polymers the alkyl side chain has been replaced by ...
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The synthesis and characterization of two novel 3-thienyl based polythiophene derivatives PT and BT have been presented. These polymers have been synthesized by convenient and ecofriendly Pd catalyzed direct arylation polymerization method. In these polymers the alkyl side chain has been replaced by alkylthienyl side chain and polymer PT analogous to regioregular poly(3-hexylthiophene) (rr-P3HT) has been synthesized. These polymers have been characterized by 1 H NMR, GPC, TGA and UV vis absorption spectroscopy. The absorption maxima of these polymers are comparable to the rr-P3HT. The polymers have very good solubility in common organic solvents and therefore the solution processing of these materials has been easily done. Solar cells of these polymers have been fabricated by using PT and BT as donor materials and PC61BM as acceptor material. It was observed that both the materials showed almost same photovoltaic characteristics. Solar cell performance of these materials has been found to be low and we are working on the optimization and improvement of power conversion efficiency of these materials.
Jiban Kangsabanik; Aftab Alam
Abstract
Hybrid perovskites (CH3NH3PbI3) is one of the most promising novel materials for solar harvesting. Toxicity of lead (Pb), however, has always remained a concern. We investigated the electronic structure of complete replacement of Pb by alkaline earths (Ca, Sr, Ba) and found them to be wide band gap (Eg) ...
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Hybrid perovskites (CH3NH3PbI3) is one of the most promising novel materials for solar harvesting. Toxicity of lead (Pb), however, has always remained a concern. We investigated the electronic structure of complete replacement of Pb by alkaline earths (Ca, Sr, Ba) and found them to be wide band gap (Eg) semiconductors (band gap ~ 3.7 to 4.0 eV), and hence not suitable as absorber material. This opens up a new avenue to explore these materials as transparent conductor (TC). We doped CH3NH3BaI3 (largest Eg) with La, which shifts its Fermi level (EF) at conduction band bottom and induces states at EF for conduction. This is precisely what is required for a transparent conductors. Optical and transport properties simulated from linear response (within Density Functional Theory (DFT)) calculations suggested it to be a very good TC material with a high figure of merit (s/a), where s is the electrical conductivity and a is the optical absorption coefficient. This claim is also supported by our calculated results on density of states at EF, effective mass, carrier concentration etc. at various La-doping. We propose CH3NH3(Ba1-xLax)I3 (x£12.5%) to be a good TC material to be used in an all perovskite solar cell.
D. Saikia; P. Phukan; M. R. Das
Abstract
Solar cells with the structure ITO-Cu-CdS/PbS-Ag were fabricated by heat-induced Chemical Bath Deposition (CBD) technique. Cu-doped CdS/PVA nanocomposite thin film of thickness 260 nm was used as the window layer. The PbS absorber layer of different thickness (528.3 -1250.8 nm) for different molar concentration ...
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Solar cells with the structure ITO-Cu-CdS/PbS-Ag were fabricated by heat-induced Chemical Bath Deposition (CBD) technique. Cu-doped CdS/PVA nanocomposite thin film of thickness 260 nm was used as the window layer. The PbS absorber layer of different thickness (528.3 -1250.8 nm) for different molar concentration of lead nitrate (0.05, 0.1, 0.15, 0.2 and 0.3 M) was then grown on ITO/CdS to fabricate the junction. The effect of molar concentrations on the optical and structural properties of the corresponding PbS films and solar cells were investigated. The optical bandgap of the PbS films was found to decrease with the increase of the molar concentration. The photovoltaic parameters such as short circuit current, open circuit voltage, fill factor and efficiency of the CdS/PbS solar cells were evaluated from the J-V characteristics under one sun illumination intensity (100mW/cm 2 ). The changing molar concentration enhanced the performances of the cells and a highest efficiency (1.38%) obtained at 0.3M molar concentration.
Vineet Kumar Singh; Jampana Nagaraju
Abstract
This paper presents the effect of emitter thickness and post-annealing process on the conversion efficiency of crystalline silicon (c-Si) solar cells. Diffusion parameters like pre-deposition temperature, drive-in temperature, and process duration assist to control the emitter thickness and inturn improves ...
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This paper presents the effect of emitter thickness and post-annealing process on the conversion efficiency of crystalline silicon (c-Si) solar cells. Diffusion parameters like pre-deposition temperature, drive-in temperature, and process duration assist to control the emitter thickness and inturn improves the conversion efficiency of the solar cells. It is observed that shallower emitter cells have higher conversion efficiency of 10.81% than deeper emitter cells of 7.62%. Post-annealing process at 700 °C for 60 minutes boosts the efficiency of shallower emitter cell from 10.81% to 12.06%. Dark current-voltage characteristics authenticate the formation of p-n junction and also elucidate the presence of recombination saturation current along with diffusion saturation current. Illuminated and dark current-voltage characteristics further provide the evidence that post-annealing process during phosphorus diffusion reduces the trap density and thus the recombination saturation current, which helps to improve the efficiency. The combination of a shallower emitter with post-annealing process provides an excellent approach to enhance the solar cell efficiency.
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