Thinnest solar cells can have thin? The latest record is 1 micron. This corresponds to one percent of the diameter of a human hair, which is one-hundredth of that of a traditional standard solar cell. Slim if achieved, then the solar cell application space will become more extensive, is no longer limited to the ground station or the roof. Photovoltaic systems can be attached to a variety of surfaces, such as wearable energy equipment as well as vehicles, appliances, and buildings. Recently, Korean scientist Juho Kim et al. Published the latest research in Applied Physics Letters and introduced the ultrathin solar cell. Although the battery is thin but its conversion efficiency is not low, the same energy can be generated compared with a solar cell with a thickness of about 3.5 μm, but the thickness is reduced to a quarter. Korean researchers have tried to combine inorganic composite semiconductor micro-cell devices with bendable or stretchable substrates to increase their flexibility by reducing the thickness of the cells. In order to make use of these micro-cell devices as portable devices for wearable electronic devices such as clothes and skins Power provides the possibility. In the past, because the electronic components need to be glued to the substrate, the adhesive would additionally increase the thickness of the battery. In this study, a new method of "cold-press-welding" was adopted. The photoresist on the top of the material was cured at 170 degrees Celsius Melt down, then solder it to the substrate electrode. The photoresist is peeled off after cooling, so the binder does not increase the cell thickness during this process. Reduce the battery thickness of microelectronic devices, is conducive to adapt to everyday use in a variety of electronic devices are extremely curved occasions. In general, the thinner the microelectronic device, the less pressure it bends when bent, and the easier it is to bend. At the same time, elastic electronic devices that are worn on the body often require continuous power supply. The experimental results and theoretical analysis just show that the ultrathin solar microbattery is more durable in extreme bending. Whether in the production cost or continuous power supply, have great advantages. The material used to make solar cells in the research is semiconductor gallium arsenide, which mainly uses the technology of transfer-printing. The repeated use of the battery is realized by the electrodes reflecting photons back to the photovoltaic cell at the bottom of the substrate. This ultra-thin solar cell is very flexible and thin, can be wrapped in pencil for a week. Many wearable devices are limited by battery size and weight and can not be used in popularization. The high flexibility and light weight of this battery will help to promote the production of wearable electronic devices, such as smart glasses and clothes. For wearable devices. In addition, the future of the material has great potential, is expected to open up many new areas for solar cell applications. Applications such as spacecraft or aerial exploration balloons that are more weight sensitive have important scientific value. Glass, fabric, paper, plastic and other materials can also be used as a battery carrier and produce greater value. In fact, the end of February this year, the Massachusetts Institute of Technology researchers have developed known as "the world's lightest thinnest" solar cells. The solar cell is 2 microns thick, twice the size of the Korean team's research and development products. Researchers said it is light and thin so it can be placed in soap bubbles without breaking it. In wearable devices, the wearable user can not even see its presence because the solar cell is very light. However, MIT solar cell conversion efficiency was not very high at the time, while the South Korean scientists to further optimize the conversion efficiency of this issue. However, the new ultra-thin solar cells developed by MIT and Korean scientists are still in the proof-of-concept stage and it will take time for them to become commercially viable.