Charge Carrier Recombination in Bulk Heterojunction Organic Solar Cells

Photovoltaic phenomenon was first observed by E. Becquerel (Becquerel) in 1839. He observed the electric current-lit silver electrode, immersed in the electrolyte. In 1894, taking advantage of the observed photoconductivity phenomenon in amorphous selenium the semiconductor solar cell was developed. The very first silicon p-n junction solar cell was made in 1954, energy conversion efficiency of which was 6% and the energy price $200/W did not seem promising for wide application. Later, the development of satellites needed to provide sustainable energy sources and the cadmium sulfid, cadmium telluride, gallium arsenide and more efficient solar cells of other materials were created. The first solar cell breakthrough was something like of the 1970 year, feeling the lack of oil, which oncreased interest in alternative energy sources. The basic raw materials, in addition to crystalline silicon, a polycrystalline silicon, were also amorphous silicon and other, suitable for thin solar cells, materials. Although, due to the high cost of these energy sources, extracted energy was only a small part of total energy production, but the lending spread as energy sources in various areas of small devices such as mobile phone, calculators, meteorogical instruments, watches and so on. A solar powered cars and even solar powered aircraft were constructed. Major Solar cells used for the purification of salt water, as well as supply power to isolated objects: mountains, islands or jungle living population. The second and much greater solar energy use breakthrough occurred in the first decade of the twenty-first century. This is caused by the earth's climate warming due to the increasing threat of thermal energy and the increasing CO2 in the atmosphere. Many governments in many ways stimulated the solar energy lending. Germany in the decade from 1994 to 2004, installed as much as 70 times more solar energy equipment, and now is installed more than 1GW: produced over 3TWh energy, which cost around 0.5 €/kWh. In Japan solar power energy is less costly than the heat. The main price of solar energy is caused by the installation consts ~ 1€/W. Till 2004 there have already been installed over 1GW, while in 2006, the world's installed 6.5 GW. In 2007, the European Union in the fight against climate warming threat committed by 2030 to achieve that 25% of the total energy from alternative sources, mainly from the Sun. It should be around 1200 GW, the cost should not exceed 0.1 €/kWh. Another reason for the needed alternative energy sources is projected oil and gas resource depletion.