Abstract
In this work we report infrared to visible upconversion luminescence in the low phonon-energy host material KPb
Cl
doped with Er
ions. The low phonon energy strongly reduces multiphonon relaxation in this host. As a consequence, in addition to the strong green upconversion luminescence from
H
,
S
) levels at room temperature, blue luminescence from
H
and
F
levels is also observed under near infrared excitation in the
I
(801 nm) and
I
(978 nm) multiplets respectively. The upconversion mechanisms are investigated by means of excitation and timeresolved luminescence spectroscopy.