Improved Ambipolar Diffusion Length in a-Si1-xGex:H Alloys for Multi-Junction Solar Cells

ABSTRACTTo prepare hydrogenated amorphous silicon-germanium alloys as low gap material for multi-junction solar cells in plasma enhanced chemical vapour deposition, the well established concept of strong dilution of the process gases with hydrogen has been used. Two different regimes of alloying were found: for low Ge content (x < 0.40) we observe material with low defect density, small Urbach energy and high values of the ambipolar diffusion length. In the regime of high Ge content (x > 0.40) the defect densities and Urbach energies are high and the values of the ambipolar diffusion length low. The transition is accompanied by the appearance of a low-temperature peak in hydrogen effusion experiments indicating a void rich film structure. Material from just above and below the transition zone is used in pin solar cells leading to a much enhanced red response compared with a-Si:H cells. The differences seen in the material quality are mirrored in the solar cell properties. By carefully adjusting the active layer thickness material with low diffusion length shows also reasonable solar cell performance.

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Annealing Kinetics of Amorphous Silicon Alloy Solar Cells Made at Various Deposition Rates

MRS Proceedings ◽

10.1557/proc-664-a25.2.1 ◽

2001 ◽

Vol 664 ◽

Cited By ~ 3

Author(s):

Baojie Yana ◽

Jeffrey Yanga ◽

Kenneth Lord ◽

Subhendu Guha

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Amorphous Silicon ◽

High Frequency ◽

Room Temperature ◽

Defect Density ◽

Very High Frequency ◽

Solar Cell Performance ◽

Kinetics Of ◽

Very High

ABSTRACTA systematic study has been made of the annealing kinetics of amorphous silicon (a-Si) alloy solar cells. The cells were deposited at various rates using H2 dilution with radio frequency (RF) and modified very high frequency (MVHF) glow discharge. In order to minimize the effect of annealing during light soaking, the solar cells were degraded under 30 suns at room temperature to quickly reach their saturated states. The samples were then annealed at an elevated temperature. The J-V characteristics were recorded as a function of annealing time. The correlation of solar cell performance and defect density in the intrinsic layer was obtained by computer simulation. Finally, the annealing activation energy distribution (Ea) was deduced by fitting the experimental data to a theoretical model. The results show that the RF low rate solar cell with high H2 dilution has the lowest Ea and the narrowest distribution, while the RF cell with no H2 dilution has the highest Ea and the broadest distribution. The MVHF cell made at 8Å/s withhigh H2 dilution shows a lower Ea and a narrower distribution than the RF cell made at 3 Å/s, despite the higher rate. We conclude that different annealing kinetics plays an important role in determining the stabilized performance of a-Si alloy solar cells.

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Hydrogenated Amorphous Silicon Germanium Alloy for Stable Solar Cells

MRS Proceedings ◽

10.1557/proc-336-487 ◽

1994 ◽

Vol 336 ◽

Cited By ~ 5

Author(s):

A. Terakawa ◽

M. Shima ◽

K. Sayama ◽

H. Tarui ◽

H. Nishiwaki ◽

...

Keyword(s):

Solar Cell ◽

Conversion Efficiency ◽

Silicon Germanium ◽

Defect Density ◽

Characteristic Energy ◽

Solar Cell Performance ◽

Germanium Content ◽

Junction Solar Cell ◽

Degradation Ratio ◽

Double Junction

ABSTRACTThe film properties and solar cell performance of a-SiGe:H samples with the same optical gap and different combinations of hydrogen content (CH) and germanium content (CGe) have been compared. The optimum composition for the initial properties, such as the tail characteristic energy, defect density and conversion efficiency of the solar cell, was determined, and the differences could be explained by the difference in H bonding configuration. The degradation ratio of the conversion efficiency becomes larger in higher CH samples. This suggests that hydrogen or Si-H2 participates in light-induced degradation. As a result, the optimum CH for an efficient solar cell is believed to shift to the lower CH region after light soaking. Based on these findings, the stabilized conversion efficiency of 3.3% under red light (γ>650nm) for an a-SiGe:H single-junction solar cell (1cm2) and 10.6% under lsun light for an a-Si/a-SiGe double-junction stacked solar cell (1cm2) have been achieved. The degradation ratio is only 8.6% for the double-junction solar cell.

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Passivation of InP solar cells using large area hexagonal-BN layers

npj 2D Materials and Applications ◽

10.1038/s41699-020-00192-y ◽

2021 ◽

Vol 5 (1) ◽

Author(s):

Vidur Raj ◽

Dipankar Chugh ◽

Lachlan E. Black ◽

M. M. Shehata ◽

Li Li ◽

...

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Surface Passivation ◽

Defect Density ◽

Hexagonal Boron Nitride ◽

Cell Structure ◽

Chemical Vapor ◽

Large Area ◽

Solar Cell Performance ◽

Passivation Layers

AbstractSurface passivation is crucial for many high-performance solid-state devices, especially solar cells. It has been proposed that 2D hexagonal boron nitride (hBN) films can provide near-ideal passivation due to their wide bandgap, lack of dangling bonds, high dielectric constant, and easy transferability to a range of substrates without disturbing their bulk properties. However, so far, the passivation of hBN has been studied for small areas, mainly because of its small sizes. Here, we report the passivation characteristics of wafer-scale, few monolayers thick, hBN grown by metalorganic chemical vapor deposition. Using a recently reported ITO/i-InP/p+-InP solar cell structure, we show a significant improvement in solar cell performance utilizing a few monolayers of hBN as the passivation layer. Interface defect density (at the hBN/i-InP) calculated using C–V measurement was 2 × 1012 eV−1cm−2 and was found comparable to several previously reported passivation layers. Thus, hBN may, in the future, be a possible candidate to achieve high-quality passivation. hBN-based passivation layers can mainly be useful in cases where the growth of lattice-matched passivation layers is complicated, as in the case of thin-film vapor–liquid–solid and close-spaced vapor transport-based III–V semiconductor growth techniques.

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Influence of the Active Layer Thickness on Non-Fullerene Polymer Solar Cell Performance

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.271.106 ◽

2018 ◽

Vol 271 ◽

pp. 106-111

Author(s):

Jun Ning ◽

Ming Ming Bao ◽

Lian Hong ◽

Hasichaolu ◽

Bolag Altan ◽

...

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Layer Thickness ◽

Active Layer ◽

Spin Coating ◽

Polymer Solar Cells ◽

Short Circuit ◽

Cell Performance ◽

Active Layer Thickness ◽

Solar Cell Performance

Research on polymer solar cells has attracted increasing attention in the past few decades due to the advantages such as low cost of fabrication, ease of processing, mechanical flexibility, etc. In recent years, non-fullerene polymer solar cells are extensively studied, because of the reduced voltage losses, and the tunability of absorption spectra and molecular energy level of non-fullerene acceptors. In this work, polymer solar cells based on conjugated polymer (PBDB-T: poly [(2,6-(4,8-bis (5-(2-ethylhexyl) thiophen-2-yl)-benzo [1,2-b:4,5-b’] dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis (2-ethylhexyl) benzo [1’,2’-c:4’,5’-c’] dithiophene-4,8-dione))]) and non-fullerene electron acceptor (ITIC: 3,9-bis (2-methylene-(3-(1,1-dicyanomethylene)-indanone)) -5,5,11,11-tetrakis (4-hexylphenyl)-dithieno [2,3-d:2’,3’-d’]-s-indaceno [1,2-b:5,6-b’] dithiophene) were prepared by means of spin-coating method, and the influence of the active layer thickness on the device performance was investigated. PBDB-T: ITIC active layers with different thickness were prepared through varying spin coating speed. It was found that the solar cell performance is best when the active layer thickness is 100 nm, corresponding to the spin coating speed of 2000 rpm. Maximum power conversion efficiency of 7.25% with fill factor of 65%, open circuit voltage of 0.85 V and short circuit current density of 13.02 Am/cm2 was obtained.

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Simulative Parametric Study on Heterojunction Thin Film Solar Cells Incorporating Interfacial Nanoclusters Layer

Energy Harvesting and Systems ◽

10.1515/ehs-2019-0004 ◽

2019 ◽

Vol 6 (1-2) ◽

pp. 23-28 ◽

Cited By ~ 1

Author(s):

Megha Grover ◽

Monika Nehra ◽

Deepak Kedia

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Layer Thickness ◽

Active Layer ◽

Interfacial Layer ◽

High Efficiency ◽

Copper Phthalocyanine ◽

Cell Performance ◽

Active Layer Thickness ◽

Solar Cell Performance

Abstract Organic solar cells deal with small organic molecules for absorption of light at low cost and high efficiency. In this paper, we have analyzed the photovoltaic (PV) characteristics of double heterojunction solar cell that consists of copper phthalocyanine (CuPc) and 3,4,9,10-perylenetetracarboxylic bis-benzimidazole (PTCBI) thin films. Here, CuPc and PTCBI layers are combined by an interfacial layer consisting of nanoscale dots. Different plasmonic materials (i. e. Ag, Au, and graphene) are selected as alternative nanoscale dot layer to examine their effect on solar cell performance. Further, the solar cell performance is also examined via variation in active layer thickness. The choice of interfacial layer material and variation in active layer thickness offer grounds for future efficient PV cells.

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Assessment of Intrinsic-Layer Growth Temperature to High-Deposition-Rate a-Si:H n-i-p Solar Cells Deposited by Hot-Wire CVD

MRS Proceedings ◽

10.1557/proc-557-163 ◽

1999 ◽

Vol 557 ◽

Cited By ~ 14

Author(s):

Qi Wang ◽

Eugene Iwaniczko ◽

Yueqin Xu ◽

Brent P. Nelson ◽

A. H. Mahan

Keyword(s):

Solar Cells ◽

Substrate Temperature ◽

Amorphous Silicon ◽

Diffusion Length ◽

Defect Density ◽

Hydrogenated Amorphous Silicon ◽

Ambipolar Diffusion ◽

Hot Wire ◽

Top Contact ◽

Hydrogenated Amorphous

AbstractWe report progress in hydrogenated amorphous silicon n-i-p solar cells with the i-layer grown by the hot-wire chemical vapor deposition technique. Early research showed that we grew device-quality materials with low saturated defect density (2 × 106/cm3), high initial ambipolar diffusion length (~2000 Å) and low hydrogen content (<1%). One of the major barriers to implementing this material into solar cells is the high substrate temperature required (>400°C). We re-assess the effects of low substrate temperature on the property of the films and the performance of the solar cells as an alternative avenue to solving this problem. We find that the material grown at 300°C can have similar values of saturated defect density and ambipolar diffusion length as the one grown greater than 400°C. We also study the effect of i-layer substrate temperature ranging from 280° to 440°C for n-i-p solar cells. We now consistently grow devices with Fill Factor (FF) greater than 0.66, with the best close to 0.70 at lower substrate temperature. A collaboration with United Solar System, in where they grew the p-layer and top contact, produced devices with initial efficiencies as high as 9.8%. We produce n-i-p solar cells with initial efficiencies as high as 8% when we grow all the hydrogenated amorphous silicon and top contact layers. All these i-layers are grown at deposition rates of 16 to 18 Å/sec. We need to further improve our p-layer and transparent conductor layer to equal the collaborative cell efficiency. We also report light-soaking results of these devices.

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Critical Assessment of Sub-Bandgap Primary Photocurrent in a-Si:H Based Solar Cells.

MRS Proceedings ◽

10.1557/proc-219-451 ◽

1991 ◽

Vol 219 ◽

Cited By ~ 2

Author(s):

T. X. Zhou ◽

S. S. Hegedus ◽

C. M. Fortmann

Keyword(s):

Solar Cells ◽

Solar Cell ◽

Defect Density ◽

Critical Assessment ◽

Cell Performance ◽

Significant Discrepancy ◽

Solar Cell Performance ◽

Before And After ◽

Degree Of Degradation

ABSTRACTThe sub-bandgap primary photocurrent and the solar cell performance of a-Si:H p-i-n devices have been studied before and after light induced degradation. The results indicate significant discrepancy between the two methods when used to estimate the degree of degradation and the defect density in the i-layers. A preliminary explanation is proposed.

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Analysis of The Efficiency In Sb2Se3 Thin-Film Solar Cells Using Alternative Buffer Layers In n-p and n-i-p Structures By Numerical Simulation.

10.21203/rs.3.rs-644062/v1 ◽

2021 ◽

Author(s):

F Ayala-Mato ◽

O Vigil-Galán ◽

Maykel Courel ◽

M. M. Nicolás-Marín

Keyword(s):

Numerical Simulation ◽

Solar Cells ◽

Solar Cell ◽

Defect Density ◽

Hole Transport ◽

Inorganic Materials ◽

Band Alignment ◽

Transport Layer ◽

Hole Transport Layer ◽

Solar Cell Performance

Abstract Antimony Sulfide (Sb2Se3) Solar Cells are considered a promising emerging photovoltaic devices technology. However, the best reported experimental efficiency (9.2%) is well below the theoretical limit of 30%. In this research is demonstrated, by numerical simulation, that using different buffer or electron transport layers (ETL) and device structures (n-p or n-i-p) can significantly increase the solar cell performance. The study is based on two underlying considerations: the use of inorganic materials to facilitate the manufacturing process and the analysis of the simulation parameters that adjust to the experimental conditions in which the cells can be processed. In the n-p structures, the use of single layers and bilayers as ETL was evaluated and the possible mechanism that explain the electrical parameters of the solar cell were discussed. Especial attention was made in the role of interfacial state density and band alignment in the ETL/Sb2Se3 interface. In addition, the n-i-p structure was studied by adding a hole transport layer (HTL). An improvement in open circuit voltage (Voc) is observed compared with n-p structure. Finally, the behavior of Voc and efficiency vs thickness of the ETL and Sb2Se3 layers was analyzed. The results show that using alternative ETLs a significant improve in Voc and efficiency could be achieved for n-p and n-i-p structures. After thickness optimization and taking account a moderate interface defect density, values of Voc and efficiency higher than 600 mV and 15 % were respectively obtained.

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Optimisation of diketopyrrolopyrrole:fullerene solar cell performance through control of polymer molecular weight and thermal annealing

Journal of Materials Chemistry A ◽

10.1039/c4ta03589e ◽

2014 ◽

Vol 2 (45) ◽

pp. 19282-19289 ◽

Cited By ~ 23

Author(s):

Zhenggang Huang ◽

Elisa Collado Fregoso ◽

Stoichko Dimitrov ◽

Pabitra Shakya Tuladhar ◽

Ying Woan Soon ◽

...

Keyword(s):

Molecular Weight ◽

Solar Cells ◽

Solar Cell ◽

Thermal Annealing ◽

Bulk Heterojunction ◽

Cell Performance ◽

Polymer Molecular Weight ◽

Solar Cell Performance ◽

Heterojunction Solar Cells ◽

Bulk Heterojunction Solar Cells

The performance of bulk heterojunction solar cells based on a novel donor polymer DPP-TT-T was optimised by tuning molecular weight and thermal annealing.

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