SELF-ASSEMBLED Ge-DOTS FOR Si SOLAR CELLS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4347-4351 ◽  
Author(s):  
H. PRESTING ◽  
J. KONLE ◽  
H. KIBBEL
Keyword(s):  
Solar Cells ◽  
Open Circuit Voltage ◽  
Elevated Temperatures ◽  
Growth Conditions ◽  
Open Circuit ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
P Type

Silicon solar cells with embedded germanium (Ge) layers deposited as 3-dimensional islands in the Stranski-Krastanov growth mode have been grown by molecular beam epitaxy (MBE) to enhance the efficiency of Si thin film solar cells. The Ge-layers increase the infrared absorption in the base of the cell to achieve higher photocurrent which should overcome the loss in the open circuit voltage due to incorporation of a smaller bandgap material in the heterostructure. Up to 75 layers of Ge, each about 8 monolayers (ML) thick, separated by Si-spacer layers (9-18nm) have been deposited at rather elevated temperatures (700°C) on a standard 10Ωcm p-type Si-substrate. Island densities of 1011 cm -2 have been achieved by use of antimony (Sb) as surfactant. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to characterize the growth of Ge-islands under variuos growth conditions. Photocurrent measurements exhibit a higher photo-response in the infrared regime but a lower open circuit voltage of the fabricated solar cells compared to a Si-reference cell.

Liquid-Phase Crystallized Silicon Solar Cells on Glass: Increasing the Open-Circuit Voltage by Optimized Interlayers for n- and p-Type Absorbers

2015 ◽  
Vol 5 (6) ◽  
pp. 1757-1761 ◽  
Author(s):  
Daniel Amkreutz ◽  
William D. Barker ◽  
Sven Kuhnapfel ◽  
Paul Sonntag ◽  
Onno Gabriel ◽  
...  
Keyword(s):  
Solar Cells ◽  
Liquid Phase ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Silicon Solar Cells ◽  
P Type

Built-in Potential and Open Circuit Voltage of Heterojunction CuIn1-xGaxSe2 Solar Cells

2005 ◽  
Vol 865 ◽  
Author(s):  
Akimasa Yamada ◽  
Koji Matsubara ◽  
Keiichiro Sakurai ◽  
Shogo Ishizuka ◽  
Hitoshi Tampo Hajime ◽  
...  
Keyword(s):  
Solar Cells ◽  
Conduction Band ◽  
Fermi Energy ◽  
Open Circuit Voltage ◽  
Material Selection ◽  
Open Circuit ◽  
Flat Band ◽  
Band Energy ◽  
Low X ◽  
P Type

AbstractThe reasons why the open circuit voltage (Voc) of high-x CuIn1-xGaxSe2 (CIGS)/ZnO solar cells remain low are discussed. Here it is shown that the Voc ceiling can be interpreted simply on the basis of a model that the valence-band energy (Ev) of CIGS is almost immovable irrespective of x. When the conduction-band energy (Ec) of ZnO is lower than that of high-x CIGS (DEc<0), the built-in potential (Vbi) of a CIGS/ZnO junction is equivalent to the flat-band potential (Vbi) that arises from the separation between the Fermi energies of the two materials. If the Ev (and therefore the Fermi energy) of p-type CIGS is constant with increasing x, the Vbi and Voc that follows the Vbi remain unchanged since the Fermi energy of ZnO is constant. This unchangeable Voc reduces the conversion efficiency of high-x CIGS cells in cooperation with reduced photocurrents due to a larger bandgap. A positive offset, ΔEc>o gives rise to a photoelectrons barrier in the conduction-band that partially cancels Voc, thus the Voc of a low-x CIGS cell is governed by the Ec of CIGS. Based upon this concept, a material selection guideline is given for the windows and transparent electrodes appropriate for high-x CIGS absorbers-based solar cells.

Increase in Open-circuit Voltage and Improved Stability of Organic Solar Cells by Inserting a Molybdenum Trioxide Buffer Layer

2009 ◽  
Vol 1154 ◽  
Author(s):  
Hideyuki Murata ◽  
Yoshiki Kinoshita ◽  
Yoshihiro Kanai ◽  
Toshinori Matsushima ◽  
Yuya Ishii
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Type Material ◽  
Type Layer ◽  
Improved Stability ◽  
The Stability ◽  
P Type

AbstractWe report the increase in open-circuit voltage (Voc) by inserting of MoO3 layer on ITO substrate to improve built-in potential of organic solar cells (OSCs). In the OSCs using 5,10,15,20-tetraphenylporphyrine (H2TPP) as a p-type material and C60 as a n-type material, the Voc effectively increased from 0.57 to 0.97 V as increasing MoO3 thickness. The obtained highest Voc (0.97 V) is consistent with the theoretical value estimated from the energy difference between the LUMO (−4.50 eV) of C60 and the HOMO (−5.50 eV) of H2TPP layer. Importantly, the enhancement in the Voc was achieved without affecting the short-circuit current density (Jsc) and the fill-factor (FF). Thus, the power conversion efficiency of the device linearly increased from 1.24% to 1.88%. We also demonstrated that a MoO3 buffer layer enhances the stability of OSCs after photo-irradiation. We have investigated the stability of OSCs using H2TPP and N,N′-di(1-naphthyl)-N,N′-diphenylbenzidine as a p-type layer. The both devices with MoO3 layer showed improved stability. These results clearly suggest that the interface at ITO/p-type layer affects the device stability.

scholarly journals Lindqvist polyoxometalates as electrolytes in p-type dye sensitized solar cells

2019 ◽  
Vol 3 (1) ◽  
pp. 96-100 ◽  
Author(s):  
Tijmen M. A. Bakker ◽  
Simon Mathew ◽  
Joost N. H. Reek
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Open Circuit Voltage ◽  
Power Conversion ◽  
Dye Sensitized Solar Cells ◽  
Open Circuit ◽  
Dye Sensitized ◽  
Redox Couples ◽  
P Type ◽  
Sensitized Solar Cells

The development of new redox couples provides a clear strategy to improve power conversion efficiency (PCE) in p-type dye-sensitized solar cells (p-DSSCs) through enabling improvements in open-circuit voltage (VOC).

Deposition of P-Type Nanocrystalline Silicon Using High Pressure in a VHF-PECVD Single Chamber System

2011 ◽  
Vol 1321 ◽  
Author(s):  
Xiaodan Zhang ◽  
Guanghong Wang ◽  
Xinxia Zheng ◽  
Shengzhi Xu ◽  
Changchun Wei ◽  
...  
Keyword(s):  
High Pressure ◽  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Nanocrystalline Silicon ◽  
Open Circuit ◽  
Single Chamber ◽  
P Type

ABSTRACTIn this article, we present a study of boron-doped hydrogenated nanocrystalline silicon (nc-Si: H) films by very high frequency-plasma enhanced chemical vapor deposition (VHF-PECVD) using high deposition pressure. Electrical, structural and optical properties of the films were investigated. Dark conductivity as high as 2.75S/cm of p-type nc-Si: H prepared at 2.5Torr pressure has been achieved at a deposition rate of 1.75Å/s for 25nm thin film. By controlling boron and phosphorus contamination, single junction nc-Si: H solar cells incorporated p-layers prepared under high pressure and low pressure, respectively, were deposited. It has been proven that nanocrystalline silicon solar cells with incorporation of p layer prepared at high pressure has resulted in enhanced open circuit voltage, short circuit current density and subsequently high conversion efficiency. Through the optimization of the bottom solar cell and application of ZnO/Al back reflector, 10.59% initial conversion efficiency of micromorph tandem solar cell (1.027cm2) with an open circuit voltage of 1.3864V, has been fabricated, where the bottom solar cell using a high pressure p layer was deposited in a single chamber.

Thermal Stability and Analysis of Laser Deposited Platinum Films

2000 ◽  
Vol 624 ◽  
Author(s):  
G.J. Berry ◽  
J.A. Cairns ◽  
M.R. Davidson ◽  
Y.C. Fan ◽  
A.G. Fitzgerald ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photoelectron Spectroscopy ◽  
Elevated Temperatures ◽  
Surface Composition ◽  
Direct Write ◽  
Force Microscopy ◽  
Annealing Conditions ◽  
Atomic Force ◽  
Transmission Electron ◽  
Induced Decomposition

ABSTRACTAs the trend towards device miniaturisation continues, surface effects and the thermal stability of metal deposits becomes increasingly important. We present here a study of the morphology and composition of platinum films, produced by the UV-induced decomposition of organometallic materials, under various annealing conditions. The surface composition of the metal deposits was studied by X-ray photoelectron spectroscopy, both as-deposited and following thermal treatment. In addition, the morphology of the surface was studied by atomic force microscopy which enabled the investigation of film restructuring. These studies were performed over a range of temperatures up to 1000°C in air and up to 600°C in reducing environments. Complementary information regarding the film morphology has been obtained from transmission electron microscopy. The data has been used to provide an insight into the effects of elevated temperatures on metal films deposited by a direct write method

Numerical 3D-Simulation of Micromorph Silicon Thin Film Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
Stefan Geißendörfer ◽  
Karsten von Maydell ◽  
Carsten Agert
Keyword(s):  
Solar Cells ◽  
Complex Refractive Index ◽  
Silicon Thin Film ◽  
3 Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Optical Generation ◽  
Surface Topographies ◽  
2D And 3D ◽  
Optical Generation Rate

ABSTRACTIn this contribution 1, 2 and 3-dimensional simulations of micromorph silicon solar cells are presented. In order to simulate solar cells with rough interfaces, the surface topographies were measured via atomic force microscopy (AFM) and transferred into the commercial software Sentaurus TCAD (Synopsys). The model of the structure includes layer thicknesses and optoelectronic parameters like complex refractive index and defect structure. Results of the space resolved optical generation rates by using of the optical solver Raytracer are presented. The space resolved optical generation rate inside the semiconductor layers depends on the structure of the transparent conductive oxides (TCO) interface. In this contribution the influence of different optical generation rates on the electrical characteristics of the solar cell device are investigated. Furthermore, the optical and electrical results of the 1D, 2D and 3D structures, which have equal layer thicknesses and optoelectronic parameters, are compared.

Study of Defects in p-type Layers in III-nitride Laser Diode Structures Grown by Molecular Beam Epitaxy

2006 ◽  
Vol 955 ◽  
Author(s):  
Huixin Xiu ◽  
Pedro MFJ Costa ◽  
Matthias Kauer ◽  
Tim M Smeeton ◽  
Stewart E Hooper ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Extended Defects ◽  
Tem Analysis ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
P Type ◽  
Nitride Laser ◽  
Cladding Layers

ABSTRACTThis paper reports on the study of defects in p-type layers in III-nitride laser structures grown by molecular beam epitaxy. Characterization of the heterostructures was carried out using atomic force microscopy and transmission electron microscopy. The results show that a high density of extended defects – possibly inversion domains – exist in the p-type cladding layers of as-grown structures with either AlGaN/GaN superlattices or bulk AlGaN cladding layers. TEM analysis of operated and aged devices does not reveal any significant structural modification of the p-type material which might be the cause of deterioration in the lasing performance or failure.

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