The Influence Of Non-equilibrium Carriers Combinationg Mechanism On Organic Solar Cells

Organic solar cell is a kind of important renewable resources, widely distributed on the earth, as ever, an inexhaustible, with the depletion of fossil fuel and serious environment pollution in recent years. The development of solar energy has been rapid development. But its maximum conversion efficiency is only 10%. So to improve the conversion efficiency of solar energy has been main trend of research in recent years.This thesis is based on organic solar cells, find the main reason of effect the conversion efficiency, passion and continuity equation can be solved iteratively by a numerical. The main work and conclusion in this thesis are listed as follows:1 Introduction to the development of bulk heterojunction solar cells, structure, and photovoltaic properties, as well as its working principle, A simulation based on charge transfer state recombination of BHJ organic solar cells. we just simulated solar absorption spectrum, through the calculation of absorption spectrum more accurately find out the rate of solar energy. The distribution of potential, current density, carrier density, net generation rate, electric field, and energy level on short circuit and open circuit are simulated2. Recombination in organic solar cells is the key loss mechanism and it directly affects power conversion efficiency and affects the optical characteristics of solar cells.The organic solar cell recombination mechanism include Langervin recombination,trap-assisted recombination, and recombination via tail. However, which recombination play the main role is still controversial. In this work, the trap-assisted Shockley-Read-Hall(SRH) recombination proposed by Kuik is extended by considering the two factors. The first one is the density of state(DOS) for recombination centers in SRH process, The second factor is the contribution of trapped carriers to electric potential in Poisson equation. The third factor is that the mobility usually being taken as constant, but it should be a function of charge carrier density or electric field. The extended model is applied to typical devices with experimental data about open circuit voltage(Voc) with light intensity(Pin) which having been used to distinguish recombination processes. The results show that these experimental data can be uniformly well fitted and explained by using the extended model no matter low light intensity or high light intensity.