|Phase Separation in Bulk Heterojunctions of Semiconducting Polymers and Fullerenes for Photovoltaics
|Year of Publication
|N.D. Treat, and M.L. Chabinyc
|Johnson, MA, and TJ Martinez
|ANNUAL REVIEW OF PHYSICAL CHEMISTRY, VOL 65
|Annual Review of Physical Chemistry
|4139 EL CAMINO WAY, PO BOX 10139, PALO ALTO, CA 94303-0897 USA
|Thin-film solar cells are an important source of renewable energy. The most efficient thin-film solar cells made with organic materials are blends of semiconducting polymers and fullerenes called the bulk heterojunction (BHJ). Efficient BHJs have a nanoscale phase-separated morphology that is formed during solution casting. This article reviews recent work to understand the nature of the phase-separation process resulting in the formation of the domains in polymer-fullerene BHJs. The BHJ is now viewed as a mixture of polymer-rich, fullerene-rich, and mixed polymer-fullerene domains. The formation of this structure can be understood through fundamental knowledge of polymer physics. The implications of this structure for charge transport and charge generation are given.