We assess the possibility to use an ambipolar organic light-emitting transistor structure as gain medium for an electrically pumped laser. Singlet and triplet continuity equations are solved together with Poissons and drift-diffusion equations in two dimensions. The solution allows for a detailed balance between the exciton decay, quenching and generation mechanisms. Simulations of a tetracene light-emitting transistor show that triplets are most dominant in quenching singlets. Singlet–triplet quenching can ultimately prevent pure tetracene crystals or films—when provided with a realistic optical feedback structure, to reach the threshold for stimulated emission.
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Since the hole and electron mobilities are not equal, the light-emission zone will not be exactly in the middle at those conditions, but still far from the contacts.