Importance of Defect Density near the p-i Interface for a-Si:H Solar Cell Performance

2001 ◽  
Vol 664 ◽  
Author(s):  
B.A. Korevaar ◽  
C. Smit ◽  
R.A.C.M.M. van Swaaij ◽  
D.C. Schram ◽  
M.C.M. van de Sanden

ABSTRACTA cascaded arc expanding thermal plasma is used to deposit intrinsic hydrogenated amorphous silicon at growth rates larger than 2 Å/s. Implementation into a single junction p-i-n solar cell resulted in initial efficiencies of ∼7%, although all the optical and initial electrical properties of the individual layers are comparable with RF-PECVD deposited films. The somewhat lower efficiency is due to a smaller fill factor. Spectral response measurements, illuminated J,V- measurements, and simulations indicate that a higher local defect density in the region near the p-i interface might be responsible for the smaller fill factor in comparison with conventional low- rate RF-PECVD. The higher defect density is most likely caused by the initial growth in the first 10 to 50 nm. Therefore, controlled initial growth of the intrinsic layer is suggested for good solar cell performance.

1992 ◽  
Vol 45 (1) ◽  
pp. 99 ◽  
Author(s):  
AM Al-Dhafiri

The influence of dark and light etching of CdS single crystals on the electrical and optical characteristics of the CdS-Cu",S heterojunction is investigated. It is shown through currentvoltage characteristics, spectral response and junction capacitance measurements that the junction of these cells is strongly affected by the presence of light during the etching process. It is found that when the CuS is formed on an etched CdS surface under light a chalcocite phase (CU2S) is obtained. In contrast, when the CuS layer is grown on a dark etched surface a mixture phase of chalcocite and djurleite (CUI� 96S) is found.


2009 ◽  
Vol 1165 ◽  
Author(s):  
JinWoo Lee ◽  
Jeroen K.J. van Duren ◽  
Alex Pudov ◽  
Miguel Contreras ◽  
David J. Cohen

AbstractTransient photocurrent (TPI) and photocapacitance (TPC) spectroscopy have been applied to a set of compositional graded CuIn1-xGaxSe2 (CIGS) solar cell devices deposited by the vacuum co-evaporation method at the National Renewable Energy Laboratory. These measurements provide a spectral map of the optically induced release of carriers for photon energies from below 1 eV to 2 eV. By comparing the two types of spectra one can distinguish majority from minority carrier processes and they clearly reveal a higher degree of minority carrier collection for devices in which the Ga fraction increased monotonically with distance from the junction. This agrees with notions of how compositional grading improves overall cell performance. Minority carrier collection was even more strongly enhanced in sample devices incorporating v-shaped Ga-grading. Spatial profiles of the free hole carrier densities and deep acceptor concentrations were examined using drive-level capacitance profiling (DLCP). In the compositionally graded sample devices we found that the free carrier density decreased and that defect density increased with increasing Ga fraction toward back contact.


2007 ◽  
Vol 1012 ◽  
Author(s):  
Ana Kanevce ◽  
James R. Sites

AbstractSolar-cell performance degradation due to physical nonuniformities becomes more significant as the thickness of polycrystalline absorbers is reduced. “Voltage” nonuniformities such as those due to band-gap fluctuations, variations in the back-contact proximity, and areas where the absorber is completely depleted can have very significant impact on cell performance. Similarly local shunts can seriously degrade the efficiency. “Current” nonuniformities such as optical defects have generally much less impact. The analysis presented is based on Cu(In,Ga)Se2 cells, but the qualitative results should be applicable to thin-absorber devices in general. For lateral nonuniformity studies, the solar cell is simulated by a two dimensional network of parallel diodes separated by resistors. The nonuniformities are approximated by small regions of reduced photovoltage, often referred to as “weak diodes”, and by isolated shunt resistors. The weak-diode approach allows investigation of device performance as a function of the weak-diode voltage deficit, the ratio of weak-to strong-diode area, and the weak diodes' spatial distribution. Increased TCO resistance can isolate weak diodes, thus limiting the voltage loss due to nonuniformities, but increasing fill-factor losses.


2019 ◽  
Vol 7 (19) ◽  
pp. 5646-5651 ◽  
Author(s):  
Bingbing Chen ◽  
Hongwei Hu ◽  
Teddy Salim ◽  
Yeng Ming Lam

This work discusses how the behaviour of the fill factor (FF) of devices calculated from current–voltage (I–V) measurements at different light intensities can be used as a basis to assess the trap density of methylammonium lead triiodide (MAPbI3) solar cells.


1986 ◽  
Vol 70 ◽  
Author(s):  
Chris Walker ◽  
Russell Hollingsworth ◽  
Joe del Cueto ◽  
Arun Madan

The use of transparent conducting oxides (TCO) as electrical contacts in a-Si:H solar cells has stimulated interest in the multitude of effects that these layers have on a-Si:H solar cell performance. The study of a-Si:H p-i-n junctions using a TCO contact involves many factors such as, interdiffusion, transmission, reflection, and resistivity. In this paper, we attempt to distinguish between these factors through the role they play in determining the solar cell device performance. Devices were characterized via dark and illuminated current vs. voltage (I-V) measurements, and spectral response. It was found that the properties of the TCO have an important role in influencing FF and Jsc in the devices.


1991 ◽  
Vol 219 ◽  
Author(s):  
T. X. Zhou ◽  
S. S. Hegedus ◽  
C. M. Fortmann

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.


2020 ◽  
pp. 114-119

Experimental and theoretical study Porphyrin-grafted ZnO nanowire arrays were investigated for organic/inorganic hybrid solar cell applications. Two types of porphyrin – Tetra (4-carboxyphenyle) TCPP and meso-Tetraphenylporphine (Zinc-TPP)were used to modify the nanowire surfaces. The vertically aligned nanowires with porphyrin modifications were embedded in graphene-enriched poly (3-hexylthiophene) [G-P3HT] for p-n junction nanowire solar cells. Surface grafting of ZnO nanowires was found to improve the solar cell efficiency. There are different effect for the two types of porphyrin as results of Zn existing. Annealing effects on the solar cell performance were investigated by heating the devices up to 225 °C in air. It was found that the cell performance was significantly degraded after annealing. The degradation was attributed to the polymer structural change at high temperature as evidenced by electrochemical impedance spectroscopy measurements.


Sign in / Sign up

Export Citation Format

Share Document