Laser Etched Solar Cells (Laser Etching for Solar Applications)

In thin-film solar panels, laser etchingis an important tool, especially high-performance, ultra-short pulse lasers, which can provide ultra-short pulses lasting only a few seconds, which not only helps manufacturers increase production but also optimizes processing technology.

As a renewable energy source, photovoltaic energy plays a pivotal role in solving energy problems. Scientific and technological progress is an important prerequisite for achieving electricity parity consumption. For example, through technological progress, the cost of photovoltaic power generation can be reduced to close to the cost of traditional energy.

Crystalline silicon solar cells are the leading products in the current photovoltaic market, with a conversion efficiency of more than 20%. Laser etching technology is mainly used for wafer cutting and edge insulation.

The laser-assisted doping process prevents power loss caused by short circuits between the front and back of the battery. Laser etching technology is increasingly widely used in laser-assisted doping technology to improve the mobility of carriers, especially electrode contacts. In recent years, thin-film solar cells have made great progress, and industry experts expect them to occupy about 20% of the photovoltaic market in the future.

Because the thickness of the thin film used in thin-film solar cells is only a few microns, a large amount of material can be saved. Laser plays a vital role in the preparation of thin-film solar cells. The laser constructs the battery into a whole and connects it to the module, and then corrodes each module to ensure the required insulation performance.

Mature Laser Scribing Technology

Deposit conductive and photovoltaic films on large-area glass substrates to produce amorphous silicon or cadmium (Cdte) thin-film solar cell modules. After deposition on each layer of film, the film is etched with a laser so that the cells are automatically connected in series. In this way, the current of the cells and modules can be set according to the width of the cell. Precision selective non-contact laser processing technology can be reliably integrated in the production line of thin-film solar modules. Generally speaking, scribing is the continuous process of laser pulse etching. After the pulse is focused, a spot of 30~80 microns can be obtained. Therefore, on the P1 layer, the glass substrate should be etched with a pulse light (10~80ns) width.

Transparent conductive oxides (TCO, such as Zno and SnO2) usually use near-infrared 1064nm fiber laser etching technology, and the pulse repetition frequency is relatively high. The pulse repetition frequency is generally above 100kHz. The high pulse repetition frequency ensures that the incision is completely clean.

The specific processing technology should select the appropriate laser wavelength according to the material's absorption rate of the laser. The green laser etcher has a low damage threshold for silicon wafers, and the green laser can safely pass through the film and scribe the absorption layer. The scribing mechanism of P2 and P3 is the same as that of the P1 layer.

The characteristics of the laser single pulse scribing mechanism itself limit the repetition frequency of the pulse. During the processing, in order to prevent the contact surface semiconductor layer from falling off, it is necessary to repeatedly use pulses of 35~45kHz. The general corrosion threshold is about 2J/cm2, that is, 25渭J of laser energy can be concentrated in an area with a diameter of 40 microns, and the average power is very small. The average power of the green laser etcher is several watts, which can realize multi-beam parallel processing, further improving the processing efficiency.

P1.P2 and P3 are used for scribing in micro-machining. The diode pumped laser with small size, small volume and output wavelength of 1064nm and 532nm is undoubtedly a very good choice. The laser has a pulse width of 8~40ns and a repetition frequency of 1~100kHz.

Light Surface Etching Protection Technology

In order to prevent the solar cell module from being corroded or short-circuited, a margin of about 1 cm wide must be left at its edge so that the entire battery module can be encapsulated later. Sandblasting is now used to clean the edges. Despite the low investment, the sandblasting process also has a certain amount of wear. The cost of cleaning sand and preventing dust pollution. Membrane solar cell modules need to be cleaned. Low-cost, cost-effective solutions and laser etching treatment solutions are undoubtedly the best choice. Increasing the average power can achieve better processing quality. Laser etching can achieve a removal rate of 50cm2/s, and can even complete a standard-sized solar cell module in less than 30 seconds.

In fact, all edge film layers can be removed by the same pulse, and the improvement of its removal rate is closely related to the average power of the laser. This laser has a large average power and high pulse energy, and can remove a specific area at a time. This treatment method is most suitable for fiber-optic transmission laser systems, which output square or rectangular spots. After fiber transmission, the energy distribution of the laser is more uniform, thereby achieving a highly consistent removal effect. The use of parallel combination spots can increase the processing efficiency by more than 50% compared with traditional optical fibers, and reduce the pulse repetition frequency while ensuring processing safety. In addition, it can be combined with a scanning galvanometer to reduce non-productive cycles. The laser should also provide corresponding time-sharing output options to reduce non-productive time. In addition, different workstations can share the processing plan of the same laser etcher, so that the loading and unloading time of the product will not affect the production efficiency of the laser etcher.