HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 56
B19 - All-Carbon Photovoltaics
Marco Bernardi a , Priyank Kumar a , Nicola Ferralis a , Maurizia Palummo c , Shenqiang Ren b , Jeffrey
C. Grossman a
a, Dept. of Materials Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge MA, 02139, USA
b, Dept. of Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence KS, 66045, USA
c, Dept. of Physics, University of Roma Tor Vergata, Via della Ricerca Scientifica 1, Rome, 00100, Italy
We present an alternative scheme for nanostructured solar cells, where carbon
nanomaterials are the only constituents of a bulk-heterojunction active layer and fulfill the role
of absorbers, donors and acceptors, in the absence of conductive polymers.
We employed ab-initio simulations to calculate the band alignment for interfaces between
carbon nanotubes, fullerene derivative PCBM and reduced graphene oxide, showing the
presence of Type-II and Schottky heterojunctions useful for charge separation in the active
layer. We prepared all-carbon solar cells with optimized proportions of these three
components that achieved AM1.5 efficiencies up to 1.5%, with fill factors up to 70% and
increased thermal stability and lifetime compared to polymer based devices. In addition, we
show our recent results on understanding and tuning the optoelectronic properties of
hybridized Carbon-Boron Nitride sheets (see Ref. 1). We show how their interfaces with carbon
nanomaterials such as PCBM fullerene and carbon nanotubes can provide novel design
opportunities for excitonic photovoltaic devices.
Taken together, our results show the potential of all-carbon solar cells as an alternative to
polymer based ones: the key combination of high carrier mobility, visible and IR absorption
and stability under illumination makes them highly appealing for next-generation
flexible photovoltaics.
References
[1] C. Li et al., Nature Mater. 9, 430-435 (2011).
© SEFIN 2012