Organic solar cell charge generation process

Similar to organic solar cells, photocurrent generation is a multistep process in NC-polymer hybrid bulk heterojunction solar cells, as demonstrated in Figure 13.7. Briefly, when a photon is absorbed by the absorbing material, electrons are exited from the valance band (VB) to the conduction band (CB) to form excitons. The excitons diffuse to the donor/acceptor interface where charge transfer occurs, leading to the dissociation of the excitons into free electrons and holes. Driven by the... 

Through exothermic dissociation of a neutral excited state in molecule by electron transfer to an adjacent molecule. This process leads to the generation of geminately bound electron-hole pairs as precursors of free positive and negative charges in an organic solar cell. 

Fig. 4 Schematic illustration of the processes leading to photocurrent generation in organic solar cells, (a) Photon absorption in Step 1 leads to excitons that may diffuse in Step 2 to the donor/ acceptor (D/A) interface. Quenching of the exciton at the D/A interface in Step 3 leads to formation of the charge-transfer (CT) state. Note that processes analogous to Steps 1-3 may also occur in the acceptor material, (b) Charge separation in Step 4 leads to free polarons that are transported through the organic layers and collected at the electrodes in Steps 5 and 6, respectively, (c) The equilibria involved in Steps 1-4- strongly influence device efficiency...

The Charge Generation Process in Organic Solar Cells... 

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