Abstract
Organic photovoltaic cells are partiuclarly sensitive to exciton harvesting and are thus, a useful platform for the characterization of exciton diffusion. While device photocurrent spectroscopy can be used to extract the exciton diffusion length, this method is frequently limited by unknown interfacial recombination losses. We resolve this limitation and demonstrate a general, device-based photocurrent-ratio measurement to extract the intrinsic diffusion length. Since interfacial losses are not active layer specific, a ratio of the donor- and acceptor-material internal quantum efficiencies cancels this quantity. We further show that this measurement permits extraction of additional device-relevant information regarding exciton relaxation and charge separation processes. The generality of this method is demonstrated by measuring exciton transport for both luminescent and dark materials, as well as for small molecule and polymer active materials and semiconductor quantum dots. Thus, we demonstrate a broadly applicable device-based methodology to probe the intrinsic active material exciton diffusion length.
Highlights
Organic photovoltaic cells are partiuclarly sensitive to exciton harvesting and are a useful platform for the characterization of exciton diffusion
With the photocurrent-ratio method thoroughly vetted against conventional PL approaches for subphthalocyanine chloride (SubPc)-C60, we investigate exciton transport in two dark small molecule materials, boron subnaphthalocyanine chloride (SubNc) and C70 (Fig. 5a)
We demonstrate a simple photocurrent-ratio method to measure the intrinsic LD of excitonic semiconductors in bilayer photovoltaic cells
Summary
Organic photovoltaic cells are partiuclarly sensitive to exciton harvesting and are a useful platform for the characterization of exciton diffusion. While device photocurrent spectroscopy can be used to extract the exciton diffusion length, this method is frequently limited by unknown interfacial recombination losses. We further show that this measurement permits extraction of additional device-relevant information regarding exciton relaxation and charge separation processes The generality of this method is demonstrated by measuring exciton transport for both luminescent and dark materials, as well as for small molecule and polymer active materials and semiconductor quantum dots. Since many high-performing active materials are weakly luminescent or dark[7,12,35,37,38], it is essential to develop more general means to accurately probe exciton transport in working devices. Device-based methods are attractive as they probe the LD in a practical environment, as opposed to the often idealized structures utilized for PL measurements This method is applicable to all excitons regardless of photoluminescence efficiency
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
