TY - JOUR
T1 - Polymer:Nonfullerene Bulk Heterojunction Solar Cells with Exceptionally Low Recombination Rates
AU - Gasparini, Nicola
AU - Salvador, Michael
AU - Heumueller, Thomas
AU - Richter, Moses
AU - Classen, Andrej
AU - Shrestha, Shreetu
AU - Matt, Gebhard J.
AU - Holliday, Sarah
AU - Strohm, Sebastian
AU - Egelhaaf, Hans-Joachim
AU - Wadsworth, Andrew
AU - Baran, Derya
AU - McCulloch, Iain
AU - Brabec, Christoph J.
N1 - KAUST Repository Item: Exported on 2021-09-14
Acknowledgements: This project received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 607585 project OSNIRO. M.S. acknowledges primary support from a fellowship by the Portuguese Fundação para a Ciência e a Tecnologia (SFRH/BPD/71816/2010). The authors gratefully acknowledge the support of the Cluster of Excellence “Engineering of Advanced Materials” at the University of Erlangen-Nuremberg, which was funded by the German Research Foundation (DFG) within the framework of its “Excellence Initiative,” Synthetic Carbon Allotropes (SFB953), Research Training Group (GRK 1896), and Solar Technologies go Hybrid (SolTech).
PY - 2017/9/1
Y1 - 2017/9/1
N2 - Organic semiconductors are in general known to have an inherently lower charge carrier mobility compared to their inorganic counterparts. Bimolecular recombination of holes and electrons is an important loss mechanism and can often be described by the Langevin recombination model. Here, the device physics of bulk heterojunction solar cells based on a nonfullerene acceptor (IDTBR) in combination with poly(3-hexylthiophene) (P3HT) are elucidated, showing an unprecedentedly low bimolecular recombination rate. The high fill factor observed (above 65%) is attributed to non-Langevin behavior with a Langevin prefactor (β/βL) of 1.9 × 10−4. The absence of parasitic recombination and high charge carrier lifetimes in P3HT:IDTBR solar cells inform an almost ideal bimolecular recombination behavior. This exceptional recombination behavior is explored to fabricate devices with layer thicknesses up to 450 nm without significant performance losses. The determination of the photoexcited carrier mobility by time-of-flight measurements reveals a long-lived and nonthermalized carrier transport as the origin for the exceptional transport physics. The crystalline microstructure arrangement of both components is suggested to be decisive for this slow recombination dynamics. Further, the thickness-independent power conversion efficiency is of utmost technological relevance for upscaling production and reiterates the importance of understanding material design in the context of low bimolecular recombination.
AB - Organic semiconductors are in general known to have an inherently lower charge carrier mobility compared to their inorganic counterparts. Bimolecular recombination of holes and electrons is an important loss mechanism and can often be described by the Langevin recombination model. Here, the device physics of bulk heterojunction solar cells based on a nonfullerene acceptor (IDTBR) in combination with poly(3-hexylthiophene) (P3HT) are elucidated, showing an unprecedentedly low bimolecular recombination rate. The high fill factor observed (above 65%) is attributed to non-Langevin behavior with a Langevin prefactor (β/βL) of 1.9 × 10−4. The absence of parasitic recombination and high charge carrier lifetimes in P3HT:IDTBR solar cells inform an almost ideal bimolecular recombination behavior. This exceptional recombination behavior is explored to fabricate devices with layer thicknesses up to 450 nm without significant performance losses. The determination of the photoexcited carrier mobility by time-of-flight measurements reveals a long-lived and nonthermalized carrier transport as the origin for the exceptional transport physics. The crystalline microstructure arrangement of both components is suggested to be decisive for this slow recombination dynamics. Further, the thickness-independent power conversion efficiency is of utmost technological relevance for upscaling production and reiterates the importance of understanding material design in the context of low bimolecular recombination.
UR - http://hdl.handle.net/10754/625754
UR - http://onlinelibrary.wiley.com/doi/10.1002/aenm.201701561/full
UR - http://www.scopus.com/inward/record.url?scp=85028852306&partnerID=8YFLogxK
U2 - 10.1002/aenm.201701561
DO - 10.1002/aenm.201701561
M3 - Article
AN - SCOPUS:85028852306
SN - 1614-6832
VL - 7
SP - 1701561
JO - Advanced Energy Materials
JF - Advanced Energy Materials
IS - 22
ER -