Organic solar cells : Novel materials, charge transport and plasmonic studies

Solar cells--Materials;Organic semiconductors;Charge transfer

Ebenhoch, Bernd ; Samuel, Ifor D. W. ; Samuel, Ifor D. W.

University:University of St Andrews

Department:Physics & Astronomy (School of)

关键词: Solar cells--Materials;    Organic semiconductors;    Charge transfer;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/7814/BerndEbenhochPhDThesis.pdf?sequence=6&isAllowed=y

来源: DR-NTU

【 摘 要 】

Organic solar cells have great potential for cost-effective and large area electricity production, but their applicability is limited by the relatively low efficiency. In this dissertation I report investigations of novel materials and the underlying principles of organic solar cells, carried out at the University of St Andrews between 2011 and 2015.Key results of this investigation:• The charge carrier mobility of organic semiconductors in the active layer of polymer solar cells has a rather small influence on the power conversion efficiency. Cooling solar cells of the polymer:fullerene blend PTB7:PC₇₁BM from room temperature to 77 K decreased the hole mobility by a factor of thousand but the device efficiency only halved.• Subphthalocyanine molecules, which are commonly used as electron donor materials invacuum-deposited active layers of organic solar cells, can, by a slight structuralmodification, also be used as efficient electron acceptor materials in solution-deposited active layers. Additionally these acceptors offer, compared to standard fullerene acceptors,advantages of a stronger light absorption at the peak of the solar spectrum.• A low band-gap polymer donor material requires a careful selection of the acceptor material in order to achieve efficient charge separation and a maximum open circuit voltage.• Metal structures in nanometer-size can efficiently enhance the electric field and light absorption in organic semiconductors by plasmonic resonance. The fluorescence of a P3HT polymer film above silver nanowires, separated by PEDOT:PSS, increased by factor of two. This could be clearly assigned to an enhanced absorption as the radiative transition of P3HT was identical beside the nanowires.• The use of a processing additive in the casting solution for the active layer of organic solar cells of PTB7:PC₇₁BM strongly influences the morphology, which leads not only to an optimum of charge separation but also to optimal charge collection.