Laser production of thin-film solar cell module is an important tool, particularly high-performance ultra short Pulse Laser, it can provide only a few seconds duration of Ultrashort pulses, which not only helps manufacturers improve yield, but also to optimize processes.
In addressing energy issues in the future discussion, photovoltaic energy as a renewable energy plays an important role. Technological progress is an essential prerequisite to achieve consumer power parity condition, for example by technological advances to reduce the cost of PV power generation closer to traditional energy costs.
At present, of crystalline silicon solar cells are photovoltaic market leading products, the conversion efficiency of up to 20%. Crystal silicon solar cell manufacturing process, the lasers are mainly used in the wafer edge cutting and insulation.
Laser edge insulation during laser doping (doping) technology is used to prevent battery caused by short circuit between the front and back of the power loss. A growing number of lasers are used for laser-assisted in doping technology in order to improve the mobility of carriers, in particular, is especially true for electrode contact means. In the past few years, thin-film solar cells made great development, industry experts are in the hope that their future in the photovoltaic market occupies about 20% of the market share.
Thin-film solar cell coating used in only a few microns thick, so it can save a lot of material in the production. In the manufacture of thin-film solar cells, lasers play a decisive role. Throughout the manufacturing process, the laser structured and connecting the battery module, and corresponding module of the etching process, which in turn guarantees the insulation properties required.
Mature laser reticle technology
Amorphous silicon or cadmium telluride (CdTe) thin-film solar cell module in the production process, and photovoltaic thin film conductive thin films on glass substrate by depositing it in a large area. After each layer was deposited, are using laser etching on film, and a series between each battery automatically. In this way, you can set according to cell width current batteries and modules. Selective non-contact laser machining of precise and reliably integrated into the production line of thin-film solar cell module. People commonly referred to as a reticle is a single pulse laser etching of a continuous process, the pulse focused spot size of 30~80 μ m, level P1 in the reticle, pulse width is dozens of nanoseconds (10~80ns) of pulsed light on glass etching.
Transparent conductive oxide (TCO, such as ZnO, SnO2) normally uses near-infrared laser and relatively high pulse repetition rate processing. Usually associated with pulse repetition rate to more than 100kHz. High pulse repetition frequency to ensure thorough cleansing of the incision.
According to the material on laser absorption coefficient of different, you need to select the right laser processing technology for a specific wavelength. Green silicon laser damage thresholds well below the damage threshold for TCO, so after the Green laser is safe through TCO film, absorbing layer reticle. Reticle mechanism of P2, and P3 layers with the same level P1.
Characteristics of single-pulse reticle mechanism itself gave some restrictions on pulse repetition frequency. In order to prevent contact surface layers of a semiconductor fall off, required during processing of typical pulse repetition frequency is 35~45kHz. Common etch threshold is approximately 2J/cm2, or 25 μ j laser energy can be focused to a diameter of 40 μ m area, the average power is very low. Because of the Green laser Watt average power level, so that the beam after spectral beam parallel process, so as to further improve efficiency.
For P1, P2 and P3 levels of reticle applications, used in micromachining applications, output wavelength of 1064nm and 532nm compact compact diode-pumped laser is undoubtedly is certainly an ideal choice, and the pulse of the laser can provide extremely high stability. This type of laser pulse duration is 8~40ns, pulse repetition frequency is 1~100kHz.
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