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1.
We demonstrated the fabrication of n-i-p type amorphous silicon (a-Si:H) thin film solar cells using phosphorus doped microcrystalline cubic silicon carbide (μc-3C-SiC:H) films as a window layer. The Hot-wire CVD method and a covering technique of titanium dioxide TiO2 on TCO was utilized for the cell fabrication. The cell configuration is TCO/TiO2/n-type μc-3C-SiC:H/intrinsic a-Si:H/p-type μc- SiCx (a-SiCx:H including μc-Si:H phase)/Al. Approximately 4.5% efficiency with a Voc of 0.953 V was obtained for AM-1.5 light irradiation. We also prepared a cell with the undoped a-Si1−xCx:H film as a buffer layer to improve the n/i interface. A maximum Voc of 0.966 V was obtained.  相似文献   

2.
Raman scattering characteristics of intrinsic and doped hydrogenated nanocrystalline silicon films which prepared by a plasma-enhanced chemical vapor deposition system are investigated. Results indicate that Raman spectra depend intensively on microstructure and impurity in the films. Taking into account phonon confinement effect and tensile strain effect in Si nanocrystals, peak redshift of measured transverse optical modes in Raman spectra of intrinsic films can be well interpreted. With respect to Raman scattering from doped samples, besides phonon confinement effect, the peak of experimental transverse optical mode further downshifts with heightening doping level, which can be primarily assigned to impurity effect from doping. In addition, the increase in relative integral intensity ratio of transverse acoustic branch to transverse optical mode and that of longitudinal acoustic branch to transverse optical mode with decreasing mean dimension of nanocrystals and heightening doping ratio, respectively, can be ascribed to disorder. Furthermore, at the same doping level, incorporation of boron can induce higher disorder than incorporation of phosphorus in nc-Si:H films.  相似文献   

3.
The band bending at the transparent conductive oxides/hydrogenated p-doped amorphous silicon (p-a-Si:H) interface is one of the most important factors limiting the performances of HIT (Heterojunctions with Intrinsic Thin layers) solar cells. In order to study this effect, a solar cell (Indium Tin Oxide (ITO)/p-a-Si:H/i-polymorphous Si:H/n-doped crystalline silicon (n-c-Si)) simulation, focused on the front contact barrier height, has been performed. The results show that a reduction of the surface potential barrier at the interface ITO/p-layer leads to an increase of the built-in potential, and hence an increase of open circuit voltage and fill factor. We have also observed that the performance of HIT solar cells remains constant above 12nm thickness of the p-layer.  相似文献   

4.
Journal of Materials Science: Materials in Electronics - Reducing the parasitic absorption of intrinsic hydrogenated amorphous silicon [a-Si:H(i)] films is crucial for enhancing the short-circuit...  相似文献   

5.
This paper considers the intrinsic layer of hydrogenated amorphous silicon (a-Si:H) solar cells. The deposition temperatures (Td) and electrode distances (between cathode and anode, E/S) are important factors for a-Si:H solar cells. Thus, this study examines the effects of deposition temperatures and electrode distances in the intrinsic layer of a-Si:H solar cells with regard to enhanced the short-circuit current density (Jsc) and thereby conversion efficiency. It is shown that the Jsc of a-Si:H solar cells can be increased by proper choice of Td and E/S of the i-a-Si:H layers. The Jsc of the a-Si:H solar cells is largely dependent on light absorption of the i-a-Si:H layer. It is demonstrated that the absorption coefficient in an i-a-Si:H layer can be increased to provide higher Jsc under fixed thickness. Results show that the optimized parameters improve the Jsc of a-Si:H solar cells to 16.52 mA/cm2, yielding an initial conversion efficiency of 10.86%.  相似文献   

6.
The effects of the incident light intensity, the thicknesses of the donor and acceptor layers on the short-circuit current density, the distributions of carrier density, electric field and electric potentials of planar heterojunction organic solar cells were numerically studied. The results show that the short-circuit current density increases with the light intensity, and will saturate when the light intensity is sufficiently strong, the short-circuit current density first increases and then decreases with the thickness of the donor layer for a given thickness of the acceptor layer, and deceases with the acceptor thickness for a given thickness of the donor layer.  相似文献   

7.
We investigate how TiO2 nanopatterns formed onto ZnO:Al (AZO) films affect the performance of hydrogenated amorphous silicon (a-Si:H) solar cells. Scanning electron microscopy results show that the dome-shaped TiO2 nanopatterns (300 nm in diameter) having a period of 500 nm are formed onto AZO films and vary from 60 to 180 nm in height. Haze factor increases with an increase in the height of the nanopatterns in the wavelength region below 530 nm. Short circuit current density also increases with an increase in the height of the nanopatterns. As the nanopatterns increases in height, the fill factor of the cells slightly increases, reaches maximum (0.64) at 100 nm, and then decreases. Measurements show that a-Si:H solar cells fabricated with 100 nm-high TiO2 nanopatterns exhibit the highest conversion efficiency (6.34%) among the solar cells with the nanopatterns and flat AZO sample.  相似文献   

8.
Infrared absorption spectra were investigated in hydrogenated amorphous silicon (a-Si(H)) films deposited both by d.c. reactive sputtering (RS) and by r.f. glow discharge (GD) of silane. The films were deposited onto polished niobium and tungsten solar test disks to form spectrally selective absorbers for comparative photothermal and photovoltaic studies. Spectra were observed from the normal spectral reflectance from 400 to 3900 cm-1 with a Fourier transform spectrometer. Hydrogen, alloyed typically at 10–35 at.% in these a-Si films, significantly reduces the gap state density and produces IR spectra characteristic of Si-H bonding complexes depending on the deposition method and the substrate temperature TD. Comparison between RS and GD films revealed significant differences in their IR spectra. RS films show a strong Si-O-Si bonding absorption from atmospheric oxygen. GD films have a marked Si-H wagging mode absorption resolved into three components. This band is very sensitive to the deposition conditions and decays with increasing TD. The SiH3 rocking mode was identified at 500 cm-1 in the GD films. The hydrogen concentration from the IR stretching mode absorption was correlated with the H2 evolution results of McMillan and Peterson on identical films. The transition with increasing TD could be traced from the room temperature state with polymeric complexes of hydrogen to the high temperature state with the single monohydride complex.  相似文献   

9.
We have fabricated and studied an organic light emitting diode (OLED) with a p-type silicon anode and a SiO2 buffer layer between the anode and the organic layers which emits light from a semitransparent top Yb/Au cathode. The luminance of the OLED is up to 5600 cd/m2 at 17 V and 1800 mA/cm2, the current efficiency is 0.31 cd/A. Both its luminance and current efficiency are much higher than those of the OLEDs with silicon as the anodes reported previously. The enhancement of the luminance and efficiency can be attributed to an improved balance between the hole- and electron-injection through two efficient ways: 1) restraining the hole-injection by inserting an ultra-thin SiO2 buffer layer between the Si anode and the organic layers; and 2) enhancing the electron-injection by using a low work function, low optical reflectance and absorption semitransparent Yb/Au cathode.  相似文献   

10.
In this study, sputtered 50, 70 and 90 nm thick Al2O3 thin films were evaluated as a passivation layer in the process of InGaN-based blue as LEDs (Light-Emitting Diodes) in order to improve the brightness of LED lamps. For packaged LED lamps, lamps with Al2O3 passivation layer had higher brightness than ones with SiO2 passivation layer, and LED lamps with 90-nm Al2O3 passivation layer were the brightest among four kinds of lamps. Although lamps with Al2O3 passivation layer had a bias voltage 0.25 V at 20 mA forward current higher the lamps built with SiO2 passivation layer, their brightness was improved about 13.6% higher than the conventional LEDs with no change in emitting wavelength.  相似文献   

11.
Device modeling of p-i-n junction amorphous silicon solar cells has been carried out using the amorphous semiconductor analysis (ASA) simulation programme. The aim of the study was to explain the role of a buffer layer in between the p-and i-layers of the p-i-n solar cell on the external parameters such as dark current density and open circuit voltage. Investigations based on the simulation of dark I–V characteristics revealed that as the buffer layer thickness increases the dark current for a given voltage decreases.  相似文献   

12.
Hydrogenated amorphous silicon film (a-Si:H) as top cell is introduced to dye-sensitized titanium dioxide nanocrystalline solar cell (DSSC) as bottom cell to assemble a hybrid tandem solar cell. The hybrid tandem solar cell fabricated with the thicknesses a-Si:H layer of 235 nm, ZnO/Pt interlayer of 100 nm and DSSC layer of 8.5 μm achieves a photo-to-electric energy conversion efficiency of 8.31%, a short circuit current density of 10.61 mA·cm− 2 and an open-circuit voltage of 1.45 V under a simulated solar light irradiation of 100 mW·cm− 2.  相似文献   

13.
An important requirement for a very fast spectral response measurement system is the simultaneous illumination of the solar cell at multiple well defined wavelengths. Nowadays this can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths. For the purpose to measure the spectral response (SR) of amorphous silicon solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 800 nm was performed. In the here developed equipment the LED illumination is modulated in the frequency range from 100 Hz to 200 Hz and the current generated by each LED is analyzed by a Fast Fourier Transform (FFT) to determine the current component corresponding to each wavelength. The equipment provides a signal to noise ratio of 2–4 orders of magnitude for individual wavelengths resulting in a precise measurement of the SR over the whole wavelength range. The difference of the short circuit current determined from the SR is less than 1% in comparison to a conventional system with monochromator.  相似文献   

14.
Quantitative estimation of the specific contact resistivity and energy barrier at the interface between transparent conducting oxide (TCO) and hydrogenated p-type amorphous silicon carbide (a-Si1 − xCx:H(p)) was carried out by inserting an interfacial buffer layer of hydrogenated p-type microcrystalline silicon (μc-Si:H(p)) or hydrogenated p-type amorphous silicon (a-Si:H(p)). In addition, superstrate configuration p-i-n hydrogenated amorphous silicon (a-Si:H) solar cells were fabricated by plasma enhanced chemical vapor deposition to investigate the effect of the inserted buffer layer on the solar cell device. Ultraviolet photoelectron spectroscopy was employed to measure the work functions of the TCO and a-Si1 − xCx:H(p) layers and to allow direct calculations of the energy barriers at the interfaces. Especially interface structures were compared with/without a buffer which is either highly doped μc-Si:H(p) layer or low doped a-Si:H(p) layer, to improve the contact properties of aluminum-doped zinc oxide and a-Si1 − xCx:H(p). Out of the two buffers, the superior contact properties of μc-Si:H(p) buffer could be expected due to its higher conductivity and slightly lower specific contact resistivity. However, the overall solar cell conversion efficiencies were almost the same for both of the buffered structures and the resultant similar efficiencies were attributed to the difference between the fill factors of the solar cells. The effects of the energy barrier heights of the two buffered structures and their influence on solar cell device performances were intensively investigated and discussed with comparisons.  相似文献   

15.
We study the distributions of conduction band and valence band electronic states associated with hydrogenated amorphous silicon. We find that there are substantial deviations from square-root distributions of electronic states, particularly deep within the bands and within the gap region. We clearly identify where these distributions of electronic states exhibit square-root functional dependencies by fitting square-root functional forms to some experimental data. The corresponding DOS effective masses are determined, and are found to be about 2 to 4 times greater than the crystalline silicon case.  相似文献   

16.
In this paper we report on flexible a-Si:H solar cells prepared on polyethylene naphthalate (PEN) substrates using p-type hydrogenated nanocrystalline silicon thin films (p-nc-Si:H) as the window layer. The p-nc-Si:H films were prepared at low temperature (150 °C) using trimethylboron (TMB) as a dopant gas. The influence of the silane concentration (SC) on the electrical and structural properties of ultra-thin p-nc-Si:H as well as the performance of solar cells on PEN was investigated. The results show that the crystalline fraction and conductivity of p-nc-Si:H thin films diminished, while the deposition rate and RMS roughness of films increased, when the SC increases from 0.53% to 0.8%. For the a-Si:H solar cells on PEN with the non-textured electrodes, the best efficiency of 6.3% was achieved with the p-nc-Si:H thin films deposited at SC = 0.67%.  相似文献   

17.
We propose a quantitative means of characterizing the optical absorption spectrum associated with an amorphous semiconductor. In particular, for a representative hydrogenated amorphous silicon optical absorption experimental data set, through a series of least-squares linear fits of an exponential function to this experimental data set, taken over a number of optical absorption ranges, we determine how the breadth of the optical absorption tail varies along the optical absorption spectrum of hydrogenated amorphous silicon. We find that the quantitative variations in the breadth of the optical absorption tail that are found provide for a clear delineation between the different regions of the optical absorption spectrum of hydrogenated amorphous silicon. We complete this analysis by theoretically determining the form of the optical absorption spectrum using a recently developed empirical model for the density of states functions corresponding to hydrogenated amorphous silicon, this analysis providing a theoretical basis for the interpretation of our results.
Farida OrapuntEmail:
Stephen K. O’Leary (Corresponding author)Email:
  相似文献   

18.
A novel nanoplate-structured thin-film solar cell was investigated that could solve the conflict between light absorption and carrier transport in a p-type amorphous silicon carbide (a-SiC)/i-type amorphous silicon germanide (a-SiGe)/n-type amorphous silicon (a-Si) thin-film solar cell. This structure has an n-type a-Si nanoplate array on the substrate, a-SiC p-layer, and an a-SiGe i-layer which are sequentially grown along the surface of each n-type a-Si nanoplate. Under illumination by sunlight, light is absorbed along the vertical direction of the nanoplate, while the carrier transport is along the horizontal direction. The nanoplate structure may absorb most of the sunlight and provide a thinner film for the effective transport of photon-generated carriers as compared to the conventional planar structure.  相似文献   

19.
Intrinsic amorphous silicon germanium (i-a-SiGe:H) films with V, U and VU shape band gap profiles for amorphous silicon germanium (a-SiGe:H) heterojunction solar cells were fabricated. The band gap profiles of i-a-SiGe:H were prepared by varying the GeH4 and H2 flow rates during the deposition process. The use of i-a-SiGe:H with band gap profile in an absorber layer for a-SiGe:H heterojunction solar cells was investigated. The solar cell using a VU shape band gap profile shows a higher efficiency compared to other shapes. The highest efficiency obtained for an a-SiGe:H heterojunction solar cell using the VU shape band gap profile technique was 9.4% (Voc = 0.79 V, Jsc = 19.0 mA/cm2 and FF = 0.63).  相似文献   

20.
A roll-to-roll plasma deposition machine for depositing multilayered amorphous alloys has been developed. The plasma deposition machine has multiple deposition areas and processes a stainless steel substrate 16 in wide continuously. Amorphous photovoltaic thin films (less than 1 μm thick) with a six-layer structure (p-i-n-p-i-n) are deposited continuously in a single pass onto a roll of stainless steel substrate 16 in wide and 1000 ft long. Mass production of low cost tandem solar cells utilizing roll-to-roll processes is now possible. A commercial plant utilizing this plasma deposition machine for manufacturing tandem amorphous silicon alloy solar cells is now in operation.  相似文献   

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