Photoinduced charge carriers in conjugated polymer-fullerene composites studied with lightinduced electron-spin resonance Dyakonov, V.; Zoriniants, G.; Scharber, M.C.; Brabec, C.J.; Janssen, R.A.J.; Hummelen, Jan Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Detailed studies on photoinduced spins in conjugated polymer/fullerene composites using ͑cw͒ light-induced electron-spin-resonance ͑LESR͒ technique are reported. Two overlapping LESR lines are observed, from positive polarons on the polymer chains and negative charges on the fullerene moieties. Microwave power saturation studies show different relaxation times for these two spins, ruling out spin-exchange correlations, giving clear evidence of independent spins. The unusually high relaxation rate of the fullerene monoanionic spins is of intrinsic origin, and discussed in terms of a splitting of the T 1u level by a Jahn-Teller-type distortion as proposed in the literature. Further, we observed two distinct contributions to LESR signals: a prompt one and a persistent one. The excitation light intensity dependence of the prompt contributions into the P ϩ and C 60 Ϫ ESR signals is of bimolecular type (I 0.5