Pyroelectric luminescence via internal Poole-Frenkel effect

Pyroelectric luminescence is a universal property of pyroelectric materials under changing temperature. In all compounds studied, inorganic and organic, it has two possible manifestations: Short-emission bursts caused by discharge of the pyroelectric field through the surrounding atmosphere and a smooth luminescence slowly varying with temperature. This latter emission, characteristic for the specific material, still waits for an explanation. With \chem{Sn_2P_2S_6} as a sample pyroelectric we show that this luminescence arises from a release of trapped charge carriers, triggered by the pyrolectric field via the Poole-Frenkel effect