The development of new materials to increase the performance of organic solar cells is accelerating because the printing technology makes it possible to produce organic thin film solar cells at a very competitive cost. Toshiba developed a material that utilizes long wave light left unutilized for power generation. The new material prevents electrons generated by light from going out halfway by eliminating surface irregularities created in the process to print the power generation part. Toshiba built a trial organic thin film solar cell using this new material. The trial cell that is 5 cm square has a generating efficiency of 7.7%, about 1.5 times higher than the generating efficiency of the existing products. Toshiba wishes to increase the generating efficiency to 10% necessary for commercialization in two years.
Kyoto University’s Shinzaburo Ito and Hideo Ohkita developed a cell by combining two kinds of organic materials - one is liable to become positive if it gets light and the other tends to collect negative electrons - to increase the voltage to be generated. In addition, they allowed the new material to absorb more light by enlarging its molecule. Because the newly developed cell does not need expensive and precious materials, it can be produced at a lower cost than the existing products. The trial product is 3 mm in diameter and its generating efficiency is as low as 2.7%, but they are confident that they will increase the efficiency to 10% by improving its electrode.
An organic thin film cell is expected to be mass produced at a cost one third of a silicone cell, making the generation cost comparable to the generation cost of nuclear power generation. It can generate even with the room lighting besides being light and soft. Japanese companies involved in the development of organic thin film cell are busily occupied with improving printing technology and microfabrication technology in addition to developing new materials.
A 5 cm square organic thin film cell Toshiba built on trial. It has a generating capacity of 7.7%, currently the world’s highest generating capacity of this size.