Multichromophoric energy sensitization of C60 for organic photovoltaics

• Published in: Applied physics letters 2014-09, Vol.105 (11)
• Main Authors: Bartynski, Andrew N., Trinh, Cong, Kirlikovali, Kent O., Thompson, Mark E.
• Format: Article
• Language: English
• Subjects: Absorption; Applied physics; Buckminsterfullerene; Chromophores; Diffusion layers; Diffusion length; Energy conversion efficiency; ENGINEERING; Excitons; Fullerenes; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Photoelectric effect; Photoelectric emission; Photovoltaic cells; Solar cells
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4896502

In organic photovoltaics (OPVs), photocurrent generation is limited by absorption and exciton diffusion in the active layer. In this work, we describe the energy sensitization of C60 simultaneously by two chromophores at high volume concentrations (50%). This sensitization strategy takes advantage of the intense absorption of the sensitizers and the exceptional electron conduction and exciton diffusion length of C60 resulting in a 30% increase in photoresponse of the C60-based sensitized acceptor layer between λ = 450 nm and 670 nm and power conversion efficiency under simulated AM 1.5 G illumination. In (2,4-bis[4-(N,N-diphenylamino)-2,6-dihydroxyphenyl] squaraine)/C60 devices, sensitization results in an increase in JSC from 6.5 ± 0.2 mA/cm2 to 8.6 ± 0.2 mA/cm2 without compromising VOC or FF. These results demonstrate the robust nature of this sensitization scheme and its broad potential for application in OPVs.