Photocarrier drift distance in organic solar cells and photodetectors.
Light harvesting systems based upon disordered materials are not only widespread in nature, but are also increasingly prevalent in solar cells and photodetectors. Examples include organic semiconductors, which typically possess low charge carrier mobilities and Langevin-type recombination dynamics--both of which negatively impact the device performance. It is accepted wisdom that the "drift distance" (i.e., the distance a photocarrier drifts before recombination) is defined by the mobility-lifetime product in solar cells. We demonstrate that this traditional figure of merit is inadequate for describing the charge transport physics of organic light harvesting systems. It is experimentally shown that the onset of the photocarrier recombination is determined by the electrode charge and we propose the mobility-recombination coefficient product as an alternative figure of merit. The implications of these findings are relevant to a wide range of light harvesting systems and will necessitate a rethink of the critical parameters of charge transport.
Centre For Organic Photonics &Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
Martin
M
Stolterfoht
Centre For Organic Photonics &Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
Ardalan
A
Armin
College of Science, Technology and Engineering, James Cook University, Townsville 4811, Australia.
Bronson
B
Philippa
College of Science, Technology and Engineering, James Cook University, Townsville 4811, Australia.
Ronald D
RD
White
Centre For Organic Photonics &Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
Paul L
PL
Burn
Centre For Organic Photonics &Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia.
Paul
P
Meredith
Department of Solid State Electronics Vilnius University 10222 Vilnius, Lithuania.
Gytis
G
Juška
1] Centre For Organic Photonics &Electronics (COPE), School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia [2] School of Engineering and Information Technology, Murdoch University, Perth 6150, Australia.
Almantas
A
Pivrikas