Patent Monkey: LCD + Solar Cell = Smart

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Cell phone battery life has been one of the top problems since its inception. Motorola was there at the beginning, and is at least exploring smart solutions.

Motorola recently received a patent for combining an LCD screen and a solar cell on a wireless device. While the cost of such a concept makes the iPhone seem like a bargain, the concept of having a display that also can have a dual purpose of receiving light for recharging the battery makes a lot of sense.

Moto’s patent notes that this technology is better with black-only LCDs achieving up to a 75% light let-through rate. In the market, thin film solar cell development has come a ways since this technology was filed. In thin-film processing of solar cells, Wikipedia notes:

Many new solar cells use transparent thin films that are also conductors of electrical charge. The dominant conductive thin films used in research now are transparent conductive oxides (abbreviated “TCO”), and include fluorine-doped tin oxide (SnO2:F, or “FTO”), doped zinc oxide (e.g.: ZnO:Al), and indium tin oxide (abbreviated “ITO”). These conductive films are also used in the LCD industry for flat panel displays. The dual function of a TCO allows light to pass through a substrate window to the active light absorbing material beneath, and also serves as an ohmic contact to transport photogenerated charge carriers away from that light absorbing material. The present TCO materials are effective for research, but perhaps are not yet optimized for large-scale photovoltaic production. They require very special deposition conditions at high vacuum, they can sometimes suffer from poor mechanical strength, and most have poor transmittance in the infrared portion of the spectrum (e.g.: ITO thin films can also be used as infrared filters in airplane windows). These factors make large-scale manufacturing more costly.

The concept has been of interest for a number of years by a few different players including Seiko, Minolta and Sharp. Motorola’s experience in solar leading to this patent has been a bit scattered over the past thirty years.

Convenient and eco-friendly, now we just need to see more of it in the market.

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