High Efficiency Thin Film Solar Cells with Intrinsic Microcrystalline Silicon Prepared by Hot Wire CVD

2002 ◽  
Vol 715 ◽  
Author(s):  
S. Klein ◽  
F. Finger ◽  
R. Carius ◽  
B. Rech ◽  
L. Houben ◽  
...  

AbstractThin film microcrystalline silicon solar cells were prepared with intrinsic absorber layers by Hot Wire CVD at various silane concentrations and substrate temperatures. Independently from the substrate temperature, a maximum efficiency is observed close to the transition to amorphous growth, i.e. the best cells already show considerable amorphous volume fractions. A detailed analysis of the thickness dependence of the solar cell parameters in the dark and under illumination indicate a high electronic quality of the i-layer material. Solar cells with very high open circuit voltages Voc up to 600mV in combination with fill factors above 70% and high short circuit current densities jsc of 22mA/cm2 were obtained, yielding efficiencies above 9%. The highest efficiency of 9.4% was achieved in solar cells of 1.4μm and 1.8μm thickness. These cells with high Voc have considerable amorphous volume fractions in the i-layer, leading to a reduced absorption in the infrared wavelength region.

Author(s):  
Samer H. Zyoud ◽  
Ahed H. Zyoud ◽  
Naser M. Ahmed ◽  
Anupama R. Prasad ◽  
Sohaib Naseem Khan ◽  
...  

This article describes in detail the numerical modeling of a CZTS (copper zinc tin sulfide) based kesterite solar cell. The Solar Cell Capacitance Simulator -one-dimension (SCAPS-1D) software was used to simulate MO/CZTS/CdS/ZnO/FTO structured solar cells. The parameters of different photovoltaic thin-film solar cells are estimated and analyzed using numerical modeling. The effects of various parameters on the performance of the photovoltaic cell and the conversion efficiency are discussed. Since the response of the solar cell is also contingent on its internal physical mechanism, J-V characteristic measures are insufficient to characterize the behavior of a device. Different features, as well as different potential conditions, must be considered for simulation, disregarding the belief in the modeling of a solar cell. With a conversion efficiency of 25.72%, a fill factor of 83.75%, a short-circuit current of 32.96436 mA/cm2 and an open-circuit voltage of 0.64V, promising optimized results have been achieved. The findings will be useful in determining the feasibility of fabricating high-efficiency CZTS-based photovoltaic cells. The efficiency of a CZTS-based experimental solar cell is also discussed. First, the effects of experimentally developed CZTS solar cells are simulated in the SCAPS-1D environment. The experimental results are then compared to the SCAPS-1D simulated results. The conversion efficiency of an optimized system increases after cell parameters are optimized. Using one-dimensional SCAPS-1D software, the effect of system parameters such as the thickness, acceptor and donor carrier concentration densities of absorber and electron transport layers, and the effect of temperature on the efficiency of CZTS-based photovoltaic cells is investigated. The proposed results will greatly assist engineers and researchers in determining the best method for optimizing solar cell efficiency, as well as in the development of efficient CZTS-based solar cells.


2011 ◽  
Vol 1321 ◽  
Author(s):  
Takuya Matsui ◽  
Michio Kondo

ABSTRACTThis paper presents our material studies on hydrogenated microcrystalline silicon (μc-Si:H) and microcrystalline silicon-germanium alloy (μc-Si1-xGex:H) thin films for the development of high efficiency p-i-n junction solar cells. In μc-Si:H solar cells, we have evaluated the structural properties of the intrinsic μc-Si:H layers grown by plasma-enhanced chemical vapor deposition at high deposition rates (>2 nm/s). Several design criteria for the device grade μc-Si:H are proposed in terms of crystallographic orientation, grain size and grain boundary passivation. Meanwhile, in μc-Si1-xGex:H solar cells, we have succeeded in boosting the infrared response of solar cell upon Ge incorporation up to x∼0.2. Nevertheless, a degradation of solar cell parameters is observed for large Ge contents (x>0.2) and thick i-layers (> 1 μm), which is attributed to the influence of the Ge dangling bonds that act as acceptorlike states in undoped μc-Si1-xGex:H. To improve the device performance, we introduce an oxygen doping technique to compensate the native defect acceptors in μc-Si1-xGex:H p-i-n solar cells.


2001 ◽  
Vol 668 ◽  
Author(s):  
Akhlesh Gupta ◽  
I. Matulionis ◽  
J. Drayton ◽  
A.D. Compaan

ABSTRACTHigh efficiency CdTe solar cells are typically grown with CdTe thicknesses from 3 to 15 μm, although the thickness required for 90% absorption of the incident irradiation at 800 nm is only ∼1 μm. In this paper, we present the effect of CdTe thickness reduction on the performance of CdS/CdTe solar cells in which both the CdS and CdTe films were grown by sputtering. We produced a series of cells with different CdTe thickness (from 0.5 to 3.0 μm), and held the CdS thickness and back-contact-processing constant. The effect of CdTe thickness reduction on the diffusion of CdS into CdTe was studied using optical absorption and x-ray diffraction techniques. Only slight decreases occur in open-circuit voltage, short-circuit current, and fill factor with decrease in CdTe film thickness to 1.0 μm. Almost 10% efficient cells were obtained with 1 μm CdTe. Below 1 μm, all cell parameters decrease more rapidly, including the red quantum efficiency.


2013 ◽  
Vol 1536 ◽  
pp. 33-38
Author(s):  
S.W. Liang ◽  
C.H. Hsu ◽  
Y.W. Tseng ◽  
Y.P. Lin ◽  
C.C. Tsai

ABSTRACTThe n-type hydrogenated microcrystalline silicon oxide (μc-SiOX:H(n)) films with different stoichiometry have been successfully prepared by varying the CO2-to-SiH4 flow ratio in the PECVD system. By using the μc-SiOX:H(n) as a replacement for μc-Si:H(n) and ITO, the conversion efficiency of μc-Si:H single-junction and a-Si:H/μc-Si:H tandem cells were improved to 6.35% and 10.15%, respectively. The major improvement of the short circuit current density (JSC) and these cell efficiencies were originated from the increased optical absorption, which was confirmed by the quantum efficiency measurement showing increased response in the long-wavelength region. Moreover, the all PECVD process except the metal contact simplified the fabrication and might benefit the industrial production.


2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yunfeng Yin ◽  
Nasim Sahraei ◽  
Selvaraj Venkataraj ◽  
Sonya Calnan ◽  
Sven Ring ◽  
...  

Microcrystalline silicon (μc-Si:H) thin-film solar cells are processed on glass superstrates having both micro- and nanoscale surface textures. The microscale texture is realised at the glass surface, using the aluminium-induced texturing (AIT) method, which is an industrially feasible process enabling a wide range of surface feature sizes (i.e., 700 nm–3 μm) of the textured glass. The nanoscale texture is made by conventional acid etching of the sputter-deposited transparent conductive oxide (TCO). The influence of the resulting “double texture” on the optical scattering is investigated by means of atomic force microscopy (AFM) (studying the surface topology), haze measurements (studying scattering into air), and short-circuit current enhancement measurements (studying scattering into silicon). A predicted enhanced optical scattering efficiency is experimentally proven by a short-circuit current enhancementΔIscof up to 1.6 mA/cm2(7.7% relative increase) compared to solar cells fabricated on a standard superstrate, that is, planar glass covered with nanotextured TCO. Enhancing the autocorrelation length (or feature size) of the AIT superstrates might have the large potential to improve theμc-Si:H thin-film solar cell efficiency, by reducing the shunting probability of the device while maintaining a high optical scattering performance.


2001 ◽  
Vol 664 ◽  
Author(s):  
Y. Nasuno ◽  
M. Kondo ◽  
A. Matsuda

ABSTRACTHydrogenated microcrystalline silicon (µc-Si:H) p-i-n solar cells have been prepared using a conventional RF plasma-enhanced chemical vapor deposition (PECVD) method at a low process temperature of 140 °C. The low temperature deposition of µc-Si:H has been found to be effective to suppress the formation of oxygen-related donors that cause a reduction in open circuit voltage (Voc) due to shunt leakage. We demonstrate the improvement of Voc by lowering the deposition temperature down to 140, while suppressing the reduction in high short circuit current density (Jsc) and fill factor (FF). A high efficiency of 8.9% was obtained using an Aasahi-U substrate. Furthermore, by optimizing textured structures on ZnO transparent conductive oxide (TCO) substrates, an efficiency of 9.4% (Voc=0.526V, Jsc=25.3mA/cm2, FF=0.710) was obtained. In addition, relatively high efficiency of 8.1% was achieved using VHF (60MHz) plasma at a deposition rate of 12 Å/s. Thus, this low temperature deposition technique for µc-Si:H is promising for both high efficiency and high rate deposition of µc-Si:H solar cells.


2009 ◽  
Vol 1153 ◽  
Author(s):  
Rahul Dewan ◽  
Darin Madzharov ◽  
Andrey Raykov ◽  
Dietmar Knipp

AbstractLight trapping in microcrystalline silicon thin-film solar cells with integrated lamellar gratings was investigated. The influence of the grating dimensions on the short circuit current and quantum efficiency was investigated by numerical simulation of Maxwell’s equations by a Finite Difference Time Domain approach. For the red and infrared part of the optical spectrum, the grating structure leads to scattering and higher order diffraction resulting in an increased absorption of the incident light in the silicon thin-film solar cell. By studying the diffracted waves arising from lamellar gratings, simple design rules for optimal grating dimensions were derived.


2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Jun-Chin Liu ◽  
Chen-Cheng Lin ◽  
Yu-Hung Chen ◽  
Chien-Liang Wu ◽  
Chia-Ming Fan ◽  
...  

We proposed a low-cost and highly reflective liquid organic sheet silver conductor using back contact reflectors in amorphous silicon (a-Si) single junction superstrate configuration thin-film solar cells produced using a nonvacuum screen printing process. A comparison of silver conductor samples with vacuum-system-sputtered silver samples indicated that the short-circuit current density (Jsc) of sheet silver conductor cells was higher than 1.25 mA/cm2. Using external quantum efficiency measurements, the sheet silver conductor using back contact reflectors in cells was observed to effectively enhance the light-trapping ability in a long wavelength region (between 600 nm and 800 nm). Consequently, we achieved an optimal initial active area efficiency and module conversion efficiency of 9.02% and 6.55%, respectively, for the a-Si solar cells. The results indicated that the highly reflective sheet silver conductor back contact reflector layer prepared using a nonvacuum process is a suitable candidate for high-performance a-Si thin-film solar cells.


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