[18a-F104-1~12] 12.2 Characterization and Materials Physics

▲ [18a-F104-6] Electric field induced shifts of the intrinsic charge separation energies in pentacene thin films.

〇Richard Murdey¹ (1.Kyoto Univ.)

Keywords:charge transfer state, charge generation, photocurrent

Crystalline pentacene has two remarkable optical features that affect charge generation processes. First, singlet fission - the spontaneous decay of a singlet exciton into two triplet states - is unusually efficient, and, second, the first singlet transition is strongly coupled to nearby charge transfer (CT) states, leading to a high degree of mixing. The two phenomena in combination facilitates bulk intrinsic charge generation in pentacene and indeed CT transitions form the principle peaks in the photocurrent action spectra of high purity pentacene thin films. In the present work, we examine how the CT transition manifold responds to changes in the electric field. At high voltages, the relative efficiency of charge pair separation originating from the lower energy CT states is enhanced, while the transport energy is found to decrease following the Poole-Frenkel effect.