Charge Transfer and Collection in Dilute Organic Donor-Acceptor Heterojunction Blends.
basic_science · Level V
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- Record sourced from PubMed, PMID 29684283.
- Also identified by DOI 10.1021/acs.nanolett.8b00851.
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Abstract
Experimental and theoretical approaches are used to understand the role of nanomorphology on exciton dissociation and charge collection at dilute donor-acceptor (D-A) organic heterojunctions (HJs). Specifically, two charge transfer (CT) states in D-A mixed HJs comprising nanocrystalline domains of tetraphenyldibenzoperiflanthene (DBP) as the donor and C<sub>70</sub> as the acceptor are unambiguously related to the nanomorphology of the mixed layer. Alternating DBP:C<sub>70</sub> multilayer stacks are used to identify and control the optical properties of the CT states, as well as to simulate the dilute mixed heterojunctions. A kinetic Monte Carlo model along with photoluminescence spectroscopy and scanning transmission electron microscopy are used to quantitatively evaluate the layer morphology under various growth conditions. As a result, we are able to understand the counterintuitive observation of high charge extraction efficiency and device performance of DBP:C<sub>70</sub> mixed layer photovoltaics at surprisingly low (∼10%) donor concentrations.