Premium
Nanostructure and Optoelectronic Characterization of Small Molecule Bulk Heterojunction Solar Cells by Photoconductive Atomic Force Microscopy
Author(s) -
Dang XuanDung,
Tamayo Arnold B.,
Seo Junghwa,
Hoven Corey V.,
Walker Bright,
Nguyen ThucQuyen
Publication year - 2010
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201000799
Subject(s) - materials science , photoconductivity , conductive atomic force microscopy , organic solar cell , optoelectronics , indium tin oxide , nanostructure , heterojunction , open circuit voltage , acceptor , polymer solar cell , nanotechnology , solar cell , thin film , atomic force microscopy , voltage , composite material , polymer , physics , condensed matter physics , quantum mechanics
Photoconductive atomic force microscopy is employed to study the nanoscale morphology and optoelectronic properties of bulk heterojunction solar cells based on small molecules containing a benzofuran substituted diketopyrrolopyrrole ( DPP ) core (3,6‐bis(5‐(benzofuran‐2‐yl)thiophen‐2‐yl)‐2,5‐bis(2‐ethylhexyl)pyrrolo[3,4‐c]pyrrole‐1,4‐dione, DPP(TBFu) 2 , and [6,6]–phenyl‐C 71 ‐butyric acid methyl ester (PC 71 BM) , which were recently reported to have power conversion efficiencies of 4.4%. Electron and hole collection networks are visualized for blends with different donor:acceptor ratios. Formation of nanostructures in the blends leads to a higher interfacial area for charge dissociation, while maintaining bicontinuous collection networks; conditions that lead to the high efficiency observed in the devices. An excellent agreement between nanoscale and bulk open‐circuit voltage measurements is achieved by surface modification of the indium tin oxide (ITO) substrate by using aminopropyltrimethoxysilane. The local open‐circuit voltage is linearly dependent on the cathode work function. These results demonstrate that photoconductive atomic force microscopy coupled with surface modification of ITO substrate can be used to study nanoscale optoelectronic phenomena of organic solar cells.