Photonics of fullerene-conducting polymer composites and multilayered structures: new results and prospects

Abstract

The general features of charge transfer processes fullerene/conducting polymer (CP) systems, such as energetics of photoinduced charge transfer (PCT) between C 60 and CP (pi) - electronic states, geometry of (pi) -(pi) overlapping and the role of self-trapping effects to polaronic states on C 60 and CP chains on the PCT dynamics are analyzed. Persistent photoconductivity and electroluminescence quenching recently found in C 60 /CP composites additionally to photoconductivity enhancement and photoluminescence quenching observed earlier, indicate that photogenerated C 60 radicals may be extremely long living in CP matrices, due to multicharging of C 60 as suggested by us accompanied with deep self-trapping to polaron/bipolaron states. The anisotropy of PCT is proposed to arise due to orientational modulation of overlapping between polaronic rings on C 60 and CP which strongly suppresses back recombination. The strategy to increase the efficiency of C 60 CP donor-acceptor (DA) photocells by improving PCT is analyzed, particularly considering multilayered structures with polarization barriers at interfaces, and increased intralayer mobilities of carriers. To increase the efficiency of photons collection in photocells we suggest three layered D-M-A structures, with molecular 'photon pump' layers strongly absorbing photons. The prospects for novel photonic applications of various C 60 CP systems, such as NLO devices and photomodulated field effect transistors (FETs) are discussed and illustrated by the newest results. New results on superconductivity of C 60 /CP upon alkali metal doping are presented, and exciting possibilities for novel superconducting phases in this system are discussed.