Exciton-exciton annihilation in TbPO4

Nicholas E. Geacintov, Jacques Breton

David A. Ender, Michael S. Otteson, P. Darejeh +3 more

H. Glaeske, Victor A Malyshev, K.‐H. Feller

We theoretically analyze the optical response from an ultrathin film built up of oriented molecular aggregates, the operating states of which are represented by Frenkel exciton states. A four-level model, involving transitions between the ground, one-exciton and two-exciton states, exciton-exciton annihilation from the two-exciton state as well as relaxation from the annihilation level back to the one-exciton and ground states, is used for describing the film optical response. It is proved that the exciton-exciton annihilation may act not as a destructive but, on the contrary, as a constructive factor tending towards the occurrence of bistability. In particular, the effect of inhomogeneous broadening of the exciton optical transition, preventing the bistable behavior, may be suppressed considerably due to a fast exciton-exciton annihilation.

A. A. Bogdanov, Igor Viktorovich Ryzhov, А. И. Зайцев +2 more

A four-level model, involving the ground, one-exciton and two- exciton states as well as a high-lying molecular term through which the two-exciton state annihilates, is used for analyzing the bistable optical response of an ultrathin film built up of oriented molecular aggregates. We focus on the effects of inhomogeneous broadening of the exciton optical transitions and exciton-exciton annihilation on bistability of the film response. It turns out that the inhomogeneous broadening, preventing generally the occurrence of bistability, may be suppressed considerably due to a fast exciton-exciton annihilation.