electrons

Membrane bilayer heterojunction organic solar cell structure as shown in figure 2. As to the body of the organic semiconductor material absorbs a photon is produced after the hole - electron pair, electrons injected into a receptor organic semiconductor material, electron and hole separation. In this system, the electron donor for P type, N type electron acceptors for holes and electrons, which are separately transmitted to the two electrode,Gaosuibuyou Thailandsolar panels
forming a light current.
And the" Schottky type" compared to battery, the structure is characterized in that the introduction of the charge separation mechanism. Compared with silicon semiconductor, organic molecular interactions between different molecules are much weaker, between LUMO and HOMO and not through a combination of whole body in phase to form a continuous conduction band and valence band.
Carrier in organic semiconductor transmission, through charge in between the different molecular mechanism to realize the" jump", macroscopical performance is its carrier mobility is much lower than the inorganic semiconductor.
At the same time,solar modules
organic small molecule absorbs a photon is aroused, not like silicon semiconductor did in the conduction band and valence band free electrons produced in the left hole.
Optical excitation of small organic molecules, generated by electrostatic interaction is combined together with the hole - electron pair, is commonly referred to as " exciton ( Exciton )". Exciton has limited time, usually at the millisecond level, without complete separation of the electron and hole will compound ( Recombination ), released from their absorption of energy.
Obviously, not separating out free electrons and holes on the exciton, the photocurrent is no contribution. Therefore organic exciton separation efficiency on the photoelectric conversion efficiency of the battery has critical implications.
The Schottky type battery,toner exciton separation efficiency is a problem. Light stimulates the formation of excitons, only in the Schottky junction diffusion layer, rely on section electric field can be separated. Other locations on the formation of excitons, must move to the diffusion layer can be formed on the contribution of light current.
But organic dye in the exciton migration distance is limited, typically less than 10 nm. So most of excitons in the separation into the electron and hole before the compound drop. In organic battery is introduced in the heterojunction results, is obviously the exciton separation efficiency.
Electrons from the excited molecule LUMO energy into electronic receptor LUMO level, this process is essentially exciton separation. The two layer of the organic film at the interface between is not smooth.
In the process of preparation ( thermal evaporation deposition, or solution spin-coating method) the two film layer will form an interpenetrating structure, thereby interface has a larger area. In to the body material phase generated excitons, through diffusion can easily reach the interface of the two materials, the electron injection receptor material LUMO level in order to achieve the separation of charge.
At the same time, many studies showed, receptor material can also absorb corresponding frequency photon exciton, then its HOMO level hole reverse into the donor material HOMO energy level. Therefore, excitons can simultaneously in bilayer membrane formed on both sides of the interface, then through the diffusion in the interface separation. In short, relative to the Schottky type battery, the donor-acceptor double membrane structure can obviously improve the exciton separation efficiency.