Photoinduced Space Charge Effects in a-Si:H Solar Cells

1999 ◽  
Vol 557 ◽  
Author(s):  
T. Unold ◽  
T. Binnewies ◽  
R. Brüggemann ◽  
G.H. Bauer
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Space Charge ◽  
Probe Beam ◽  
Defect Density ◽  
Photon Flux ◽  
Charge Collection ◽  
Small Signal ◽  
Charge Effects ◽  
Signal Probe

AbstractWe have investigated charge collection in thin amorphous silicon solar cells under light bias illumination, both experimentally and by numerical simulation. In such charge collection experiments, space charge due to trapped bias-light generated carriers leads to an enhancement of a small signal probe beam charge collection. It is found that this enhancement of the small signal charge collection is strongly dependent on the diode thickness and the defect density in the samples. In particular for thin diodes (d < 0.5 microns) the charge collection enhancement can be shown to increase with light-induced degradation of the devices. The effect of these material parameters as well as other experimental parameters, such as light bias and probe beam photon flux, will be demonstrated by means of numerical simulation.

The Study of Space Charge Effects by Spectral Response, Steady State Charge Collection and Transient Photocurrents in Thick a-Si:H Pin-Diodes

1996 ◽  
Vol 420 ◽  
Author(s):  
J.-H. Zollondz ◽  
R. Brüggemann ◽  
S. Reynolds ◽  
C. Main ◽  
W. Gao ◽  
...  
Keyword(s):  
Steady State ◽  
Defect Density ◽  
Collection Efficiency ◽  
Spectral Response ◽  
Photon Flux ◽  
Charge Collection ◽  
Internal Variables ◽  
Pin Diodes ◽  
Charge Effects ◽  
Amplification Ratio

AbstractCharge collection, transient photocurrents and collection efficiency under additional bias illumination were used to characterize 3–4 micron thick a-Si:H pin-diodes. The wavelength dependent decrease or increase in the spectral response, depending on the bias flux and absorption depth, is related to the distribution of the electric field, recombination and majority carrier diffusion. At higher photon flux an overshoot in the transient photocurrent after switch-on of steady illumination indicates the time scale for the changes in internal variables. Collection efficiencies under large bias monochromatic photon flux well in excess of the maximum value of 100 % for probe beam generated carriers are observed with a large amplification ratio. These efficiencies sensitively depend both on the applied voltage and the defect density. Numerical modelling reveals the influence of internal variables on the transient and steady state photocurrents under the different illumination conditions.

Simulation of A-SI Pin Solar Cells with Buffer

1993 ◽  
Vol 297 ◽  
Author(s):  
P.H Pfleiderer H
Keyword(s):  
Solar Cells ◽  
Space Charge ◽  
Numerical Simulations ◽  
Inversion Layer ◽  
Surface Recombination ◽  
Small Signal ◽  
Front Side ◽  
Dipole Layer ◽  
Field Peak ◽  
Typical Cell

The buffer of standard solar cells restricts the "surface recombination" at the front side. Some typical cell properties linked to the buffer are exposed by numerical simulations: The "blue snake" appearing in small-signal photocharacteristics, the electron inversion layer, the reverse field peak and the satellite space-charge dipole layer. It is possible to base a simulation on the roots of an algebraic equation.

Effect of defect density and energy level mismatch on the performance of perovskite solar cells by numerical simulation

Optik ◽  
2019 ◽  
Vol 182 ◽  
pp. 1204-1210 ◽  
Author(s):  
M.S. Jamal ◽  
S.A. Shahahmadi ◽  
Mohd. Aizat Abdul Wadi ◽  
P. Chelvanathan ◽  
N. Asim ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Energy Level ◽  
Defect Density ◽  
Perovskite Solar Cells

scholarly journals 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.

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.

Microcrystalline (Si,Ge):H Solar Cells

2003 ◽  
Vol 762 ◽  
Author(s):  
Jianhua Zhu ◽  
Vikram L. Dalal
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Quantum Efficiency ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Defect Density ◽  
Cell Structure ◽  
Open Circuit ◽  
Base Layer ◽  
Ecr Plasma

AbstractWe report on the growth and properties of microcrystalline Si:H and (Si,Ge):H solar cells on stainless steel substrates. The solar cells were grown using a remote, low pressure ECR plasma system. In order to crystallize (Si,Ge), much higher hydrogen dilution (∼40:1) had to be used compared to the case for mc-Si:H, where a dilution of 10:1 was adequate for crystallization. The solar cell structure was of the p+nn+ type, with light entering the p+ layer. It was found that it was advantageous to use a thin a-Si:H buffer layer at the back of the cells in order to reduce shunt density and improve the performance of the cells. A graded gap buffer layer was used at the p+n interface so as to improve the open-circuit voltage and fill factor. The open circuit voltage and fill factor decreased as the Ge content increased. Quantum efficiency measurements indicated that the device was indeed microcrystalline and followed the absorption characteristics of crystalline ( Si,Ge). As the Ge content increased, quantum efficiency in the infrared increased. X-ray measurements of films indicated grain sizes of ∼ 10nm. EDAX measurements were used to measure the Ge content in the films and devices. Capacitance measurements at low frequencies ( ~100 Hz and 1 kHz) indicated that the base layer was indeed behaving as a crystalline material, with classical C(V) curves. The defect density varied between 1x1016 to 2x1017/cm3, with higher defects indicated as the Ge concentration increased.

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