Understanding the Bulk Heterojunction Structures

Still remains the most efficient device architecture for polymer solar cells up to now. 

In order to understand the remarkable improvement of device efficiency introduced by BHJ structures, the working mechanism of polymer solar cells has to be clarified. The working mechanism of organic thin-film solar cells can be broken down as follows  

Each step can be evaluated by (the absorption efficiency), (the exciton diffusion efficiency), /ct (the charge transfer efficiency), and tj Q (the carrier collection efficiency), respectively. 

The external quantum efficiency of an organic solar cell equals 

Consequently, interpenetrating phase-separated D/A network composites, that is, bulk heterojunctions, appear to be ideal photovoltaic composites. The fundamental 

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