"LG Display has unveiled an e-book that is equipped with in-house developed solar cell. The thin-film solar cell featured in the e-book measures 10 centimeters in width and length, it was developed to perfectly fit the 6-inch display panel for e-book currently mass produced by LG Display. The solar cell measures 0.7 millimeter in thickness and weighs a mere 20 grams, the less thickness of a credit card and the weight of a fountain pen. The thin-film solar cell is produced by placing electrodes onto a glass or plastic substrate. Contrary to widely adopted crystalline solar cells that employ silicon wafers, the thin-film solar cell is generally light-weight and easily adjustable in size and form for applications such as e-books or mobile phones. The current energy conversion efficiency rate of this product is approximately 9.6 percent. Exposure to sunlight for about four to five hours would extend the running time of the e-book's battery by a day without the need for additional charging. This would allow longer outdoor use of the e-book and lessens worries about battery discharging"