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Garching bei Munchen, Germany

Wang H.-Q.,Friedrich - Alexander - University, Erlangen - Nuremberg | Batentschuk M.,Friedrich - Alexander - University, Erlangen - Nuremberg | Osvet A.,Friedrich - Alexander - University, Erlangen - Nuremberg | Pinna L.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 2 more authors.
Advanced Materials | Year: 2011

With the aim of utilizing the infrared region of solar radiation to improve solar cell performance, significant progress, including theoretical analysis and experimental achievement, has been made in the field of up-conversion for photovoltaic applications. This Research News article reviews recent progress in the development of rear-earth (RE) ion doped up-conversion materials for solar cell applications. In addition, new trends for RE-ion-doped phosphors are briefly discussed, among them trivalent RE-ion-doped up-conversion materials for organic solar cell applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Azimi H.,Friedrich - Alexander - University, Erlangen - Nuremberg | Hou Y.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Bavarian Center for Applied Energy Research
Energy and Environmental Science | Year: 2014

Solution-processed organic and inorganic semiconductors offer a promising path towards low-cost mass production of solar cells. Among the various material systems, solution processing of multicomponent inorganic semiconductors offers considerable promise due to their excellent electronic properties and superior photo- and thermal stability. This review surveys the recent developments of "all solution-processed" copper-indium (-gallium)-chalcogenide (CuInS2, CuInSe2 and Cu(In, Ga)(Se, S)2) chalcopyrites and copper-zinc-tin-chalcogenide (Cu2ZnSnS4 and Cu2ZnSnSe4 (CZTS(e))) kesterite solar cells. A brief overview further addresses some of the most critical material aspects and associated loss mechanisms in chalcopyrite and kesterite devices. Today's state-of-the-art performance as well as future challenges to achieve low-cost and environmentally friendly production is discussed. This journal is © the Partner Organisations 2014. Source


Deibel C.,University of Wurzburg | Dyakonov V.,University of Wurzburg | Dyakonov V.,Bavarian Center for Applied Energy Research
Reports on Progress in Physics | Year: 2010

Organic solar cells have the potential to be low-cost and efficient solar energy converters, with a promising energy balance. They are made of carbon-based semiconductors, which exhibit favourable light absorption and charge generation properties, and can be manufactured by low temperature processes such as printing from solvent-based inks, which are compatible with flexible plastic substrates or even paper. In this review, we will present an overview of the physical function of organic solar cells, their state-of-the-art performance and limitations, as well as novel concepts to achieve a better material stability and higher power conversion efficiencies. We will also briefly review processing and cost in view of the market potential. © 2010 IOP Publishing Ltd. Source


Deibe C.,University of Wurzburg | Strobe T.,University of Wurzburg | Strobe T.,University of Cambridge | Dyakonov V.,University of Wurzburg | Dyakonov V.,Bavarian Center for Applied Energy Research
Advanced Materials | Year: 2010

Charge transfer complexes are interfacial charge pairs residing at the donor-acceptor heterointerface in organic solar cell. Experimental evidence shows that it is crucial for the photovoltaic performance, as both photocurrent and open circuit voltage directly depend on it. For charge photogeneration, charge transfer complexes represent the intermediate but essential step between exciton dissotiation and charge extraction. Recombination of free charges to the ground state is via the bound charge transfer state before being lost to the ground state. In terms of the open circuit voltage, its maximum achievable value is determined by the energy of the charge transfer state. An important question is whether or not maximum photocurrent and maximum open circuit voltage can be achieved simultaneously. The impact of increasing the CT energy-in order to raise the open circuit voltage, but lowering the kinetic excess energy of the CT complexes at the same time-on the charge photogeneration will accordingly be discussed. Clearly, the fundamental understanding of the processes involving the charge transfer state is essential for an optimisation of the performance of organic solar cells © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Ameri T.,Friedrich - Alexander - University, Erlangen - Nuremberg | Li N.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Friedrich - Alexander - University, Erlangen - Nuremberg | Brabec C.J.,Bavarian Center for Applied Energy Research
Energy and Environmental Science | Year: 2013

Multi-junction solar cell configurations, where two or further sub-cells with complementary absorption are stacked and connected in series or parallel, offer an exciting approach to tackle the single junction limitations of organic solar cells and further improve their power conversion efficiency. In this article we aim to follow up our previous work and review the most important and novel developments that have been recently reported on organic tandem solar cells. In addition, some brief theoretical considerations addressing the potential of single and tandem solar cells, the working principles of the intermediate layer, the importance and benefits of optical simulations and finally the intricacies of a precise performance measurement of bulk-heterojunction organic tandem solar cells based on complementary absorber materials are presented. © 2013 The Royal Society of Chemistry. Source

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