scholarly journals Solar Cells Efficiency enhancement using multilevel Selective Energy Contacts (SECs)

2021 ◽  
Author(s):  
Mohammad Eskandari ◽  
Azeez Barzinjy ◽  
Ali Rostami ◽  
Ghasem Rostami ◽  
Mahboubeh Dolatyari
Keyword(s):  
Solar Cells ◽  
Conduction Band ◽  
Energy Levels ◽  
High Energy ◽  
Maximum Efficiency ◽  
Efficiency Enhancement ◽  
Hot Carrier ◽  
Extra Energy ◽  
Typical Material ◽  
Carrier Extraction

Abstract High-energy coming photons can be absorbed and lead to generate hot carriers. In normal solar cells, these carriers are scattered, by electron-electron and electron-lattice mechanisms, and rapidly lose extra energy then approach the conduction band energy edge. This event in addition to other loss mechanisms causes the efficiency reduction in the solar cells to a limited value, theoretically 33%. Accordingly, the efficiency of solar cells can be enhanced considerably, if one makes the possibility for carriers that can be extracted rapidly before scattering and releasing extra energy to the lattice. This type of solar cell is called hot carrier solar cells (HCSCs). To this end, to improve the conversional efficiency, multilevel energy selective contacts (ESCs) as a new concept and new mechanism in solar cells can be utilized. In the other words, several appropriate energy levels as carrier extraction contacts in the conduction band are introduced. Here, we use multilevel ESCs, and based on our simulation it is shown that the maximum efficiency of 75% is achievable for low bandgap materials. For a typical material such as Si, the maximum efficiency is increased to 60% using ten ESCs.

Hot-Carrier Extraction in InAs/GaAs Quantum Dot Superlattice Solar Cells

2019 ◽  
Author(s):  
Yukihiro Harada ◽  
Naoto Iwata ◽  
Daiki Watanabe ◽  
Shigeo Asahi ◽  
Takashi Kita
Keyword(s):  
Solar Cells ◽  
Quantum Dot ◽  
Hot Carrier ◽  
Gaas Quantum Dot ◽  
Carrier Extraction

Benzoporphyrins bearing pyridine or pyridine-N-oxide anchoring groups as sensitizers for dye-sensitized solar cell

2016 ◽  
Vol 20 (01n04) ◽  
pp. 542-555 ◽  
Author(s):  
Benjamin Schmitz ◽  
Bihong Li ◽  
R. G. Waruna Jinadasa ◽  
Shashi B. Lalvani ◽  
Lei L. Kerr ◽  
...  
Keyword(s):  
Solar Cells ◽  
Energy Level ◽  
Conduction Band ◽  
Spectroscopic Data ◽  
Energy Levels ◽  
Dye Sensitized Solar Cells ◽  
Dye Sensitized ◽  
Oxidation Potentials ◽  
Anchoring Groups ◽  
Sensitized Solar Cells

Novel benzoporphyrins bearing pyridine or pyridine-[Formula: see text]-oxide groups were prepared through a concise method based on a Pd0 catalyzed cascade reaction. These benzoporphyrins were examined as sensitizers for dye-sensitized solar cells. Vicinal pyridine and vicinal pyridine-[Formula: see text]-oxide groups were introduced as new types of anchoring/acceptor groups for dye-sensitized solar cells for the first time. While all the porphyrins showed solar to electricity conversion, benzoporphyrins bearing pyridine-[Formula: see text]-oxide anchoring groups displayed higher conversion efficiency than benzoporphyrins bearing pyridine-anchoring groups.Opp-dibenzoporphyrins display broadened and red-shifted UV-vis absorption and emission bands as compared with those of the monobenzoporphyrins, which arises from the fusion of one more benzene ring and the attachment of two more electron-withdrawing groups to the porphyrin [Formula: see text]-positions. Cyclic voltammetry (CV) data and DFT calculation data obtained for these porphyrins agree well with their UV-vis absorption and fluorescence spectroscopic data. The HOMO energy level derived from the first oxidation potentials indicate that regeneration of the resulting porphyrin radical cation by the redox mediator (I[Formula: see text]/I[Formula: see text] is thermodynamically feasible for all these benzoporphyrin sensitizers (3, 5, 8 and 10). On the other hand, excited state energy levels of these benzoporphyrins calculated from the CV data, the UV-vis and fluorescence spectroscopic data are all slightly lower than the energy level of the conduction band of TiO2, suggesting insufficient driving force for efficient electron injection from the porphyrin excited singlet state to the conduction band of TiO2.

scholarly journals Fundamental Issues in Manufacturing Photovoltaic Modules Beyond the Current Generation of Materials

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
G. F. Alapatt ◽  
R. Singh ◽  
K. F. Poole
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Self Assembly ◽  
New Techniques ◽  
Current Generation ◽  
Intermediate Band ◽  
Hot Carrier ◽  
Carrier Multiplication ◽  
Processing Techniques ◽  
Carrier Extraction

Many methods to improve the solar cell’s efficiency beyond current generation of bulk and thin film of photovoltaic (PV) devices have been reported during the last five decades. Concepts such as multiple exciton generations (MEG), carrier multiplication (CM), hot carrier extraction, and intermediate band solar cells have fundamental flaws, and there is no experimental evidence of fabricating practical higher efficiency solar cells based on the proposed concepts. To take advantages of quantum features of nanostructures for higher performance PV devices, self-assembly-based bottom-up processing techniques are not suitable for manufacturing due to inherent problems of variability, defects, reliability, and yield. For processing nanostructures, new techniques need to be invented with the features of critical dimensional control, structural homogeneity, and lower cost of ownership as compared to the processing tools used in current generations of bulk and thin-film solar cells.

Promoting Hot Carrier Extraction in Zn-Ag-In-Te Nanocrystals By Irradiation of High-Energy Light

2020 ◽  
Vol MA2020-02 (27) ◽  
pp. 1880-1880
Author(s):  
Tatsuya Kameyama ◽  
Kota Sugiura ◽  
Susumu Kuwabata ◽  
Tomoki Okuhata ◽  
Naoto Tamai ◽  
...  
Keyword(s):  
High Energy ◽  
Hot Carrier ◽  
Carrier Extraction

scholarly journals Theoretical Modelling of High-efficiency Perovskite Solar Cells and Reduction of Internal Heat Generation using Hot-Electron Extraction

2021 ◽  
Author(s):  
Ali Rostami ◽  
Isun Tofigi ◽  
Azeez Barzinjy ◽  
Hamit Mirtagioglu
Keyword(s):  
Solar Cells ◽  
Heat Generation ◽  
Near Infrared ◽  
High Efficiency ◽  
Perovskite Solar Cells ◽  
Internal Heat ◽  
High Energy ◽  
Theoretical Modelling ◽  
Hot Electron ◽  
Efficiency Enhancement

Abstract Perovskite single crystals have received enormous attention in recent years. This is, perhaps, due to their simplistic synthesis and excellent optoelectronic properties including the long carrier diffusion length, high carrier mobility, low trap density, and tuneable absorption edge ranging from ultra-violet (UV) to near-infrared (NIR). These distinguishing features offer numerous potential applications in energy-related fields like solar cells, photodetectors (PDs), lasers, etc. Efficiency enhancement and stability, in general, are the main challenges to obtain better solar cells. One of the main reasons for the early degradation of solar cells is heat generation due to high energy electrons and holes in the conduction and valance bands. In this study, the authors trying to introduce the concept of selective energy contacts in perovskite solar cells. Also, they investigate how this concept affects the power conversion efficiency (enhancement) and heat generation due to hot electrons and holes (reduction) scattering in the conduction and valance bands. Both efficiency enhancement and reduction in heat generation have been calculated in this study. Thus, for mathematical modeling of the anticipated idea, the Methylammonium lead halide (CH3NH3PbI3) material is used in a PIN structure for a single-junction solar cell. Also, for the proposed structure, analytical modeling was introduced and it is shown that the efficiency of a single contact cell is around 25%, and after applying the second contact, the efficiency was increased to 35%. Finally, due to the reduction of heat loss in the structure, the stability of perovskite material is significantly increased.

scholarly journals Design of Grating Al2O3 Passivation Structure Optimized for High-Efficiency Cu(In,Ga)Se2 Solar Cells

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4849
Author(s):  
Chan Hyeon Park ◽  
Jun Yong Kim ◽  
Shi-Joon Sung ◽  
Dae-Hwan Kim ◽  
Yun Seon Do
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
Surface Passivation ◽  
Rear Surface ◽  
Maximum Efficiency ◽  
Structural Factors ◽  
Carrier Recombination ◽  
Cigs Solar Cells ◽  
Effective Carrier ◽  
Opening Width

In this paper, we propose an optimized structure of thin Cu(In,Ga)Se2 (CIGS) solar cells with a grating aluminum oxide (Al2O3) passivation layer (GAPL) providing nano-sized contact openings in order to improve power conversion efficiency using optoelectrical simulations. Al2O3 is used as a rear surface passivation material to reduce carrier recombination and improve reflectivity at a rear surface for high efficiency in thin CIGS solar cells. To realize high efficiency for thin CIGS solar cells, the optimized structure was designed by manipulating two structural factors: the contact opening width (COW) and the pitch of the GAPL. Compared with an unpassivated thin CIGS solar cell, the efficiency was improved up to 20.38% when the pitch of the GAPL was 7.5–12.5 μm. Furthermore, the efficiency was improved as the COW of the GAPL was decreased. The maximum efficiency value occurred when the COW was 100 nm because of the effective carrier recombination inhibition and high reflectivity of the Al2O3 insulator passivation with local contacts. These results indicate that the designed structure has optimized structural points for high-efficiency thin CIGS solar cells. Therefore, the photovoltaic (PV) generator and sensor designers can achieve the higher performance of photosensitive thin CIGS solar cells by considering these results.

scholarly journals The Use of Lasers in Dental Materials: A Review

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3370
Author(s):  
Emmanouil-George C. Tzanakakis ◽  
Evangelos Skoulas ◽  
Eudoxie Pepelassi ◽  
Petros Koidis ◽  
Ioannis G. Tzoutzas
Keyword(s):  
Energy Levels ◽  
Dental Materials ◽  
High Strength ◽  
Surface Characteristics ◽  
High Energy ◽  
Zirconia Ceramics ◽  
Material Management ◽  
Laboratory Procedures ◽  
Laser Devices ◽  
Exact Point

Lasers have been well integrated in clinical dentistry for the last two decades, providing clinical alternatives in the management of both soft and hard tissues with an expanding use in the field of dental materials. One of their main advantages is that they can deliver very low to very high concentrated power at an exact point on any substrate by all possible means. The aim of this review is to thoroughly analyze the use of lasers in the processing of dental materials and to enlighten the new trends in laser technology focused on dental material management. New approaches for the elaboration of dental materials that require high energy levels and delicate processing, such as metals, ceramics, and resins are provided, while time consuming laboratory procedures, such as cutting restorative materials, welding, and sintering are facilitated. In addition, surface characteristics of titanium alloys and high strength ceramics can be altered. Finally, the potential of lasers to increase the adhesion of zirconia ceramics to different substrates has been tested for all laser devices, including a new ultrafast generation of lasers.

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