Dramatic photoluminescence quenching of phenylene vinylene oligomer thin films upon submonolayer Ca deposition

We report that Ca atoms severely quench the photoluminescence (PL) of an organic thin film 1,4-bis[4-(3,5-di-tert-butylstyryl)stryyl]benzene (4PV). A submonolayer coverage (0.035 monolayer or 0.1 Å) of Ca on the 4PV surface reduced the PL of a 300 Å layer of 4PV by as much as 50%. Three distinct quenching rates were observed throughout the 200 Å Ca deposition. An exciton diffusion length of 200 Å in 4PV is estimated assuming that the PL quenching is diffusion controlled.