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Carrier Transport and Recombination in Efficient “All‐Small‐Molecule” Solar Cells with the Nonfullerene Acceptor IDTBR
Author(s) -
Liang RuZe,
Babics Maxime,
Savikhin Victoria,
Zhang Weimin,
Le Corre Vincent M.,
Lopatin Sergei,
Kan Zhipeng,
Firdaus Yuliar,
Liu Shengjian,
McCulloch Iain,
Toney Michael F.,
Beaujuge Pierre M.
Publication year - 2018
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201800264
Subject(s) - polymer solar cell , active layer , acceptor , materials science , organic solar cell , charge carrier , recombination , solar cell , fullerene , polymer , electron mobility , optoelectronics , nanotechnology , chemistry , layer (electronics) , organic chemistry , physics , biochemistry , condensed matter physics , composite material , gene , thin film transistor
Reaching device efficiencies that can rival those of polymer‐fullerene Bulk Heterojunction (BHJ) solar cells (>10%) remains challenging with the “All‐Small‐Molecule” (All‐SM) approach, in part because of (i) the morphological limitations that prevail in the absence of polymer and (ii) the difficulty to raise and balance out carrier mobilities across the active layer. In this report, the authors show that blends of the SM donor DR3TBDTT (DR3) and the nonfullerene SM acceptor O‐IDTBR are conducive to “All‐SM” BHJ solar cells with high open‐circuit voltages ( V OC ) >1.1 V and PCEs as high as 6.4% (avg. 6.1%) when the active layers are subjected to a post‐processing solvent vapor‐annealing (SVA) step with dimethyl disulfide (DMDS). Combining electron energy loss spectroscopy (EELS) analyses and systematic carrier recombination examinations, the authors show that SVA treatments with DMDS play a determining role in improving charge transport and reducing non‐geminate recombination for the DR3:O‐IDTBR system. Correlating the experimental results and device simulations, it is found that substantially higher BHJ solar cell efficiencies of >12% can be achieved if the IQE and carrier mobilities of the active layer are increased to >85% and >10 −4 cm 2 V −1 s −1 , respectively, while suppressing the recombination rate constant k to <10 −12 cm 3 s −1 .