Direct observation of trapped carriers in polydiacetylene films by optical second harmonic generation

摘要

Trapped carriers in polydiacetylene (PDA) films were directly observed by the electric field induced second harmonic generation (EFISHG) using field effect transistor (FET) structure. Response of EFISHG signal from PDA-FET with applying voltage depended strongly on the polarity of gate voltage. For negative bias, which promotes hole injection from source electrode, EFISHG signal was not observed during bias application, whereas it was enhanced after turning off the bias. Electric field formed by trapped holes in PDA activated the EFISHG signal for the negative bias condition.