In this study, metal‐assisted etching (MAE) with nitric acid (HNO3) as a hole injecting agent has been employed to texture multi‐crystalline silicon wafers. It was previously proven that addition of HNO3 enabled control of surface texturing so as to form nano‐cone shaped structures rather than nanowires. The process parameters optimized for optically efficient texturing have been applied to multi‐crystalline wafers. Fabrication of p‐type Al:BSF cells have been carried out on textured samples with thermal SiO2/PECVD‐SiNx stack passivation and screen printed metallization. Firing process has been optimized in order to obtain the best contact formation. Finally, jsc enhancement of 0.9 mA/cm2 and 0.6% absolute increase in the efficiency have been achieved. This proves that the optimized MAE texture process can be successfully used in multi‐crystalline wafer texturing with standard passivation methods.
J –V curves and SEM images of the nano and iso‐textured samples. jsc enhancement of 0.9 mA/cm2 together with 0.6% absolute efficiency gain was observed on nano‐textured samples. 相似文献
For polycrystalline silicon thin films on glass, E-beam evaporation capable of high-rate deposition of amorphous silicon (a-Si) film precursor up to 1 μm/minute is a potentially low-cost solution to replace the main stream a-Si deposition method—plasma enhanced chemical vapour deposition (PECVD). Due to weak absorption of near infrared light and a target of 2 μm Si absorber thickness, glass substrate texturing as a general way of light trapping is vital to make E-beam evaporation commercially viable. As a result, the compatibility of e-beam evaporation with glass textures becomes essential. In this paper, glass textures with feature size ranging from ~200 nm to ~1.5 micron and root-mean-square roughness (Rms) ranging from ~10 nm to 200 nm are prepared and their compatibility with e-beam evaporation is investigated. This work indicates that e-beam evaporation is only compatible with small smooth submicron sized textures, which enhances Jsc by 21 % without degrading Voc of the cells. Such textures improve absorption-based Jsc up to 45 % with only 90 nm SiNx as the antireflection and barrier layer; however, the enhancement degrades to ~10 % with 100 nm SiOx+90 nm SiNx as the barrier layer. The absorption-based Jsc is abbreviated by Jsc(A), which is deduced by integrating the multiplication product of the measured absorption and the AM1.5G spectrum in the wavelength range 300–1050 nm assuming unity internal quantum efficiency at each wavelength. This investigation is also relevant to other thin-film solar cell technologies which require evaporating the absorber onto textured substrate/superstrate. 相似文献
The preferred (002) orientation zinc oxide (ZnO) nanocrystalline thin films have been deposited on FTO-coated glass substrates
by sol–gel spin-coating technology and rapid thermal annealing for use in dye-sensitized solar cells (DSSC). The effects of
preannealing temperature (100 and 300°C) on the microstructure, morphology and optical properties of ZnO thin films were studied.
The ZnO thin films were characterized by X-ray diffraction (XRD), scanning electron microscopic (SEM) and Brunauer–Emmett–Teller
(BET) analysis. The photoelectric performance of DSSC was studied by I–V curve and the incident photon-to-current conversion efficiency (IPCE), respectively. From the results, the intensities of
(002) peaks of ZnO thin films increases with increasing preannealing temperature from 100°C to 300°C. The increase in pore
size and surface area of ZnO films crystallized at the increased preannealing temperature contributed to the improvement on
the absorption of N3 dye onto the films, the short-circuit photocurrent (Jsc) and open-circuit voltage (Voc) of DSSC. The higher efficiency (η) of 2.5% with Jsc and Voc of 8.2 mA/cm2 and 0.64 V, respectively, was obtained by the ZnO film preannealed at 300°C. 相似文献
A?novel method of combining photolithography, wet chemical etching and oxidation process was proposed to fabricate large area of silicon microwire (SiMW) arrays. The dimensions of the SiMWs can be easily controlled by photomask and etching conditions. Solar cells based on the heterojunction between SiMW and double-walled carbon nanotubes (DWNTs) were constructed. The initial test on the DWNT/SiMW shows efficiency (??) of?0.59%. By adding a few drops of HBr/B2 electrolyte, the efficiency was improved to 1.96% with Jsc=19.2?mA/cm2 and Voc=0.35?V, FF=29.2%, showing the potential of SiMWs in photovoltaic applications. 相似文献
The metal–insulator transition (MIT) behavior in vanadium dioxide (VO2) epitaxial film is known to be dramatically affected by interfacial stress due to lattice mismatching. For the VO2/TiO2 (001) system, there exists a considerable strain in ultra‐thin VO2 thin film, which shows a lower Tc value close to room temperature. As the VO2 epitaxial film grows thicker layer‐by‐layer along the “bottom‐up” route, the strain will be gradually relaxed and Tc will increase as well, until the MIT behavior becomes the same as that of bulk material with a Tc of about 68 °C. Whereas, in this study, we find that the VO2/TiO2 (001) film thinned by “top‐down” wet‐etching shows an abnormal variation in MIT, which accompanies the potential relaxation of film strain with thinning. It is observed that even when the strained VO2 film is etched up to several nanometers, the MIT persists, and Tc will increase up to that of bulk material, showing the trend to a stress‐free ultra‐thin VO2 film. The current findings demonstrate a facial chemical‐etching way to change interfacial strain and modulate the phase transition behavior of ultrathinVO2 films, which can also be applied to other strained oxide films. 相似文献
In this paper, Tunnel Oxide Passivated Contact (TOPCon) silicon solar cells with the industrial area (244.32 cm2) are fabricated on N-type silicon substrates. Both the ultra-thin tunnel oxide layer and phosphorus doped polycrystalline silicon (polysilicon) thin film are prepared by the LPCVD system. The wrap-around of polysilicon is observed on the surface of borosilicate glass (BSG). The polysilicon wrap-around can form a leakage current path, thus degrades the shunt resistance of solar cells, and leads to the degradation of solar cell efficiency. Different methods are adopted to treat the polysilicon wrap-around and improve shunt resistance of solar cells. The experimental results indicate that a chemical etching method can effectively solve the problem of polysilicon wrap-around and improve the performance of solar cells. Finally, a conversion efficiency of 22.81% has been achieved by our bifacial TOPCon solar cells, with Voc of 702.6 mV, Jsc of 39.78 mA/cm2 and FF of 81.62%. 相似文献
A simple, low-cost, post-black etching process atop the random pyramidal emitter has been proposed and investigated. The multi-scale texture is achieved by combining nanoporous layer formed by the post-black etching with micron-scale pyramid texture. Compared to the pre-black etched Si solar cells, our experiments clearly show the advantage of post-black etched texturing: it enables high blue response and improved conversion efficiency. As a result, the enhancement of 7.1 mA/cm2 on the short-circuit current density and improvement of 31 % in the conversion efficiency have been reached. 相似文献
Low resistance dye-sensitized solar cells (DSSCs) based on all-titanium substrates were proposed in this paper. To minimize the internal resistance of DSSCs, the titanium wires and titanium sheets were used as the substrates of the photoanode and the counter electrode, respectively. Compared with the FTO substrate, titanium wires could absorb much diffused light by back reflection since the reflectivity in the titanium sheet was highly increased up to 53.12%. Furthermore, the transmittance of the front cover was increased by 13.2% using the super white glass instead of FTO substrate. The thickness of TiO2 thin film coated on titanium wire was optimized to achieve a high cell performance. The efficiency of 5.6% for the cell was obtained with a Jsc of 15.41 mA cm−2, Voc of 0.59 V, and FF of 0.62. The results showed that the titanium-based DSSCs had superiority for producing the large-scale DSSCs without metal grid line. 相似文献
We design the InGaP/GaAs dual-junction (DJ) solar cells by optimizing short-circuit current matching between top and bottom
cells using the Silvaco ATLAS. The relatively thicker base layer of top cell exhibits a larger short-circuit current density
(Jsc) while the thicker base layer of bottom cell allows for a smaller Jsc. The matched Jsc of 10.61±0.05 and 13.25±0.06 mA/cm2 under AM1.5G and AM0 illuminations, respectively, are obtained, leading to the increased conversion efficiency. The base
thicknesses of top InGaP cells are optimized at 0.8 and 0.65 μm for AM1.5G and AM0 illuminations, respectively, and the base thicknesses of bottom GaAs cells are optimized at 2 μm. For the optimized solar cell structure, the maximum Jsc = 10.66 mA/cm2 (13.31 mA/cm2), Voc = 2.34 V (2.35 V), and fill factor = 87.84% (88.1%) are obtained under AM1.5G (AM0) illumination, exhibiting a maximum
conversion efficiency of 25.78% (23.96%). The effect of tunnel diode structure, i.e, GaAs/GaAs, AlGaAs/AlGaAs, and InGaP/InGaP,
on the characteristics of solar cells is investigated. The photogeneration rate in the DJ solar cell structure is also obtained
by incident light of different wavelengths. 相似文献
This paper reports the use of graphite thin films as a counter electrode of a solid state photoelectrochemical cells of ITO/TiO2/PVC-LiClO4/graphite. The photoelectrochemical cells material was a screen-printed layer of titanium dioxide onto an ITO-covered glass
substrate which was used as a working electrode of the device. The solid electrolyte used was PVC-LiClO4 that was prepared by solution casting technique. The graphite films which serve as a counter electrode were prepared onto
glass substrate by electron beam evaporation technique at substrate temperatures variation of 25, 50, 100, 150 and 200 °C.
The dependence of sheet resistance and surface morphology of the graphite films on substrate temperature were studied. The
films deposited at 25 °C shows the smoothest surface morphology and the smallest grain size. Bigger grain size, rougher surface
morphology of graphite film counter electrode. The current-voltage characteristics of four devices utilising the graphite
counter electrode with different substrate temperature in dark as well as under illumination of 100 mWcm−2 light from a tungsten halogen lamp were recorded at room temperature and at 50 °C, respectively. It was found that the photovoltaic
parameters of the device such as short-circuit current density, Jsc and open-circuit voltage, Voc increases with the decreasing average grain size of the graphite counter electrode. The device whose graphite film counter
electrode was deposited onto the glass substrate at 25 °C gave the highest Jsc of 0.32 μA/cm2 and Voc of 117 mV, respectively. 相似文献