scholarly journals A Theoretical Model for Voltage-Dependent Photocurrent Collection in CdTe Solar Cells

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1615
Author(s):  
Cindy X. Zhao ◽  
Ken K. Chin
Keyword(s):  
Thin Film ◽  
Experimental Data ◽  
Solar Cells ◽  
Solar Cell ◽  
Theoretical Model ◽  
Output Voltage ◽  
Collection Efficiency ◽  
Cdte Thin Film ◽  
Doping Density ◽  
Cdte Solar Cells

The classic solar cell model assumes that the photo-generated current is a constant, independent of the cell’s output voltage. Experimental data of CdTe solar cells, however, show that the photocurrent collection efficiency decreases with the increase of the cell’s output voltage. In this work, we proposed a theoretical model for the CdTe thin-film cell, which assumes that the loss of photocurrent in the CdTe absorber is primarily due to the minority carrier recombination in the neutral region and at the back contact. By solving the neutral region’s diffusion equation, with proper boundary conditions, we have obtained the analytical expressions of the photocurrent collection efficiency and the cell’s J-V performance. Our theoretical results agree well with the experimental data. According to our theoretical model, the CdTe thin-film solar cell has an optimized p-doping level. A higher doping density may not be always good for a CdTe solar cell due to the reduced depletion width and decreased photocurrent at normal operation voltage, although the higher doping density can improve the open-circuit voltage by increasing built-in voltage.

Preparation of the Three Main Layers of CdS/CdTe Thin Film Solar Cells Using a Single Vacuum System

2011 ◽  
Vol 378-379 ◽  
pp. 601-605 ◽  
Author(s):  
Saleh N. Alamri ◽  
M. S. Benghanem ◽  
A. A. Joraid
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Fused Silica ◽  
Vacuum System ◽  
Cdte Thin Film

This study investigates the preparation of the three main layers of a CdS/CdTe thin film solar cell using a single vacuum system. A Close Space Sublimation System was constructed to deposit CdS, CdTe and CdCl2 solar cell layers. Two hot plates were used to heat the source and the substrate. Three fused silica melting dishes were used as containers for the sources. The properties of the deposited CdS and CdTe films were determined via Atomic force microscopy, scanning electron microscopy, X-ray diffraction and optical transmission spectroscopy. An J-V characterization of the fabricated CdS/CdTe solar cells was performed under solar radiation. The short-circuit current density, Jsc, the open-circuit voltage, Voc, fill factor, FF and conversion efficiency, η, were measured and yielded values of 27 mA/cm2, 0.619 V, 58% and 9.8%, respectively.

First-principles Study of Back Contact Effects on CdTe Thin Film Solar Cells

2010 ◽  
Vol 1268 ◽  
Author(s):  
Mao-Hua Du
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
First Principles ◽  
Cell Performance ◽  
Thin Film Solar Cells ◽  
Back Contact ◽  
Cdte Thin Film ◽  
Solar Cell Performance ◽  
Cdte Solar Cells ◽  
P Type

AbstractForming a chemically stable low-resistance back contact for CdTe thin film solar cells is critically important to the cell performance. This paper reports theoretical study of the effects of the back contact material, Sb2Te3, on the performance of the CdTe solar cells. First-principles calculations show that Sb impurities in p-type CdTe are donors and can diffuse with low diffusion barrier. There properties are clearly detrimental to the solar cell performance. The Sb segregation into the grain boundaries may be required to explain the good efficiencies for the CdTe solar cells with Sb2Te3 back contacts.

scholarly journals Effect ofIn SituThermal Annealing on Structural, Optical, and Electrical Properties of CdS/CdTe Thin Film Solar Cells Fabricated by Pulsed Laser Deposition

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Alaa Ayad Al-mebir ◽  
Paul Harrison ◽  
Ali Kadhim ◽  
Guanggen Zeng ◽  
Judy Wu
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Solar Cells ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Thin Film Solar Cells ◽  
Cdte Thin Film ◽  
Cdte Solar Cells ◽  
Cdte Thin Films

Anin situthermal annealing process (iTAP) has been introduced before the commonex situcadmium chloride (CdCl2) annealing to improve crystal quality and morphology of the CdTe thin films after pulsed laser deposition of CdS/CdTe heterostructures. A strong correlation between the two annealing processes was observed, leading to a profound effect on the performance of CdS/CdTe thin film solar cells. Atomic force microscopy and Raman spectroscopy show that the iTAP in the optimal processing window produces considerable CdTe grain growth and improves the CdTe crystallinity, which results in significantly improved optoelectronic properties and quantum efficiency of the CdS/CdTe solar cells. A power conversion efficiency of up to 7.0% has been obtained on thin film CdS/CdTe solar cells of absorber thickness as small as 0.75 μm processed with the optimal iTAP at 450°C for 10–20 min. This result illustrates the importance of controlling microstructures of CdTe thin films and iTAP provides a viable approach to achieve such a control.

Structural Properties of CdTe Thin Films for Solar Cell Applications Deposited on Flexible Foil Substrates

2009 ◽  
Vol 1165 ◽  
Author(s):  
Vasilios Palekis ◽  
Deidra Ranel Hodges ◽  
Don L Morel ◽  
Lee Stefanakos ◽  
Chris S Ferekides
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Growth Rate ◽  
Grain Size ◽  
Solar Cells ◽  
Solar Cell ◽  
Substrate Temperature ◽  
Source Temperature ◽  
Cdte Solar Cells ◽  
Cdte Thin Films

AbstractCadmium telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal band gap of 1.45 eV and its high optical absorption coefficient. The typical CdTe thin film solar cell is of the superstrate configuration where a window layer (CdS), the absorber (CdTe), and a back contact are deposited onto a glass slide coated with a transparent electrode. Substrate CdTe solar cells where the above listed films are deposited in reverse order are not common. In this study, the growth of CdTe thin films deposited on foil substrates by the close-spaced sublimation (CSS) has been investigated for the purpose of fabricating substrate based CdTe solar cells. The CdTe films were deposited at substrate temperatures (TSUB) in the range of 300 to 600°C, and source temperatures (TSRC) in the 600 to 650°C range. The effect of the substrate-source temperature variations on the growth rate, film structure and morphology were studied using XRD and SEM. It was found that for low substrate temperature and as the growth rate increases, grain size was the same but the films appeared to be more uniform and more densely packed with less or no pinholes. The growth rate increased as the source temperature increased. The substrate temperature clearly influences the grain growth and the preferred orientation. As the substrate temperature increased the growth rate decreased and the grain size varied from 2 to 6 μm. XRD analysis showed that with the increase in substrate temperature film orientation changes from preferential along the (111) direction to a mix of (111) (220) and (311).

High efficiency CdTe solar cells with a through-thickness polycrystalline CdTe thin film

RSC Advances ◽  
2016 ◽  
Vol 6 (57) ◽  
pp. 52326-52333 ◽  
Author(s):  
Kai Shen ◽  
Zhizhong Bai ◽  
Yi Deng ◽  
Ruilong Yang ◽  
Dezhao Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Liquid Phase ◽  
Growth Mechanism ◽  
High Efficiency ◽  
Cdte Thin Film ◽  
Preferential Growth ◽  
Cdte Solar Cells ◽  
Crystalline Growth

CdTe preferential growth with through-thickness grains has been achieved. A crystalline growth mechanism assisted by an oxide liquid phase is proposed.

Cu K-edge EXAFS Studies Of CdCl2 Effects On CdTe Solar Cells

2005 ◽  
Vol 865 ◽  
Author(s):  
Xiangxin Liu ◽  
Alvin D. Compaan ◽  
Jeff Terry
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Grain Boundary ◽  
Cdte Thin Film ◽  
X Ray ◽  
Cdte Solar Cells ◽  
Cdte Films ◽  
Chloride Treatment ◽  
P Type ◽  
X Ray Absorption

AbstractThe highest performance CdS/CdTe thin film solar cells are generally completed with a Cucontaining back contact. The copper appears to be critical for achieving heavy p-type doping of the CdTe at the contact to permit the formation of a low resistance contact. In previous extended x-ray absorption fine structure (EXAFS) work we have inferred that most of the Cu in CdTe films resides as Cu2O at the boundaries of CdTe grains in films that have received a chloride treatment in the presence of oxygen, a critical step needed to improve the performance of all CdTe thin-film cells. This has suggested a mechanism for grain boundary passivation in thinfilm CdTe solar cells. We believe most of the diffused Cu decorates grain boundaries as oxides, consistent with the low doping densities typically observed in CdTe solar cells. The significance for grain boundary passivation will be discussed. We also find evidence that the grain-boundary Cu2O in CdCl2 treated CdTe films is unstable and tends to transform to CuO under some stress conditions.

Interface Engineering of Chalcogenide Semiconductors in Thin Film Solar Cells: CdTe as an Example

2001 ◽  
Vol 668 ◽  
Author(s):  
J. Fritsche ◽  
D. Kraft ◽  
A. Thissen ◽  
Th. Mayer ◽  
A. Klein ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Surface Science ◽  
Thin Film Solar Cells ◽  
Cdte Thin Film ◽  
Solar Cell Performance ◽  
Energy Diagram ◽  
Band Energy ◽  
As Doping

ABSTRACTIn this paper the electronic properties of the different interfaces of CdTe thin film solar cells will be analysed by using a surface science approach. Experimental basis for the experiments is an integrated UHV systems which allows to prepare and analyse real solar cells as well as appropriate model interfaces. Recently obtained data on the ITO surface, the ITO/SnO2/CdS front contact, the CdS/CdTe heterojunction and the CdTe/Te back contact will be presented. In addition, bulk properties as doping and lateral inhomogeneities will be addressed. For all these interfaces experimentally determined band energy diagrams will be given and discussed in relation to solar cell performance. Finally, the sum of the results will be used to propose a modified band energy diagram of the complete CdTe thin film solar cell and its implication for further cell improvement will be presented.

scholarly journals Numerical Investigation of Graphene as a Back Surface Field Layer on the Performance of Cadmium Telluride Solar Cell

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3275
Author(s):  
Devendra KC ◽  
Deb Kumar Shah ◽  
M. Shaheer Akhtar ◽  
Mira Park ◽  
Chong Yeal Kim ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Doping Concentration ◽  
Carrier Lifetime ◽  
Short Circuit ◽  
Back Surface ◽  
Back Surface Field ◽  
Cdte Solar Cell ◽  
Cdte Solar Cells ◽  
Surface Field

This paper numerically explores the possibility of ultrathin layering and high efficiency of graphene as a back surface field (BSF) based on a CdTe solar cell by Personal computer one-dimensional (PC1D) simulation. CdTe solar cells have been characterized and studied by varying the carrier lifetime, doping concentration, thickness, and bandgap of the graphene layer. With simulation results, the highest short-circuit current (Isc = 2.09 A), power conversion efficiency (h = 15%), and quantum efficiency (QE ~ 85%) were achieved at a carrier lifetime of 1 × 103 ms and a doping concentration of 1 × 1017 cm−3 of graphene as a BSF layer-based CdTe solar cell. The thickness of the graphene BSF layer (1 mm) was proven the ultrathin, optimal, and obtainable for the fabrication of high-performance CdTe solar cells, confirming the suitability of graphene material as a BSF. This simulation confirmed that a CdTe solar cell with the proposed graphene as the BSF layer might be highly efficient with optimized parameters for fabrication.

scholarly journals Plasmon-Enhanced Sunlight Harvesting in Thin-Film Solar Cell by Randomly Distributed Nanoparticle Array

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1380
Author(s):  
Marwa M. Tharwat ◽  
Ashwag Almalki ◽  
Amr M. Mahros
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Near Infrared ◽  
Structural Parameters ◽  
Visible Region ◽  
Nanoparticle Array ◽  
Solar Energy Harvesting ◽  
Infra Red ◽  
Crucial Parameter

In this paper, a randomly distributed plasmonic aluminum nanoparticle array is introduced on the top surface of conventional GaAs thin-film solar cells to improve sunlight harvesting. The performance of such photovoltaic structures is determined through monitoring the modification of its absorbance due to changing its structural parameters. A single Al nanoparticle array is integrated over the antireflective layer to boost the absorption spectra in both visible and near-infra-red regimes. Furthermore, the planar density of the plasmonic layer is presented as a crucial parameter in studying and investigating the performance of the solar cells. Then, we have introduced a double Al nanoparticle array as an imperfection from the regular uniform single array as it has different size particles and various spatial distributions. The comparison of performances was established using the enhancement percentage in the absorption. The findings illustrate that the structural parameters of the reported solar cell, especially the planar density of the plasmonic layer, have significant impacts on tuning solar energy harvesting. Additionally, increasing the plasmonic planar density enhances the absorption in the visible region. On the other hand, the absorption in the near-infrared regime becomes worse, and vice versa.

scholarly journals CdTe-Based Thin Film Solar Cells: Past, Present and Future

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1684
Author(s):  
Alessandro Romeo ◽  
Elisa Artegiani
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Early Years ◽  
Solar Cell Efficiency ◽  
Cell Efficiency

CdTe is a very robust and chemically stable material and for this reason its related solar cell thin film photovoltaic technology is now the only thin film technology in the first 10 top producers in the world. CdTe has an optimum band gap for the Schockley-Queisser limit and could deliver very high efficiencies as single junction device of more than 32%, with an open circuit voltage of 1 V and a short circuit current density exceeding 30 mA/cm2. CdTe solar cells were introduced at the beginning of the 70s and they have been studied and implemented particularly in the last 30 years. The strong improvement in efficiency in the last 5 years was obtained by a new redesign of the CdTe solar cell device reaching a single solar cell efficiency of 22.1% and a module efficiency of 19%. In this paper we describe the fabrication process following the history of the solar cell as it was developed in the early years up to the latest development and changes. Moreover the paper also presents future possible alternative absorbers and discusses the only apparently controversial environmental impacts of this fantastic technology.

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