PROBING BURIED ORGANIC LAYERS IN ORGANIC LIGHT-EMITTING DIODES UNDER OPERATION BY ELECTRIC-FIELD-INDUCED DOUBLY RESONANT SUM-FREQUENCY GENERATION SPECTROSCOPY

"Probing buried organic layers in organic light-emitting diodes under operation by electric-field-induced doubly resonant sum-frequency generation spectroscopy". T. Miyamae, N. Takada, T. Tsutsui. APPLIED PHYSICS LETTERS 101, 073304 (2012). DOI: 10.1063/1.4746273

Electric-field-induced doubly resonant sum-frequency generation (EFI-DR-SFG) spectroscopy was used to study the electric field distribution in multilayer organic light-emitting diodes (OLEDs). Remarkable correlations between the DR-SFG signal enhancement and the applied bias voltage were observed. The SFG signals attributed to 4,4′-bis[N-(1-naphthyl-N-phenylamino)-biphenyl] were significantly enhanced by applying a forward voltage, whereas those from Alq₃ were increased by applying a reverse voltage. The large enhancement in EFI-DR-SFG intensity enables us to nondestructively probe the local electric field distribution at the buried organic layer within the OLED.

Se utilizó espectroscopia resonante de generación doble de suma de frecuencias inducida por campo eléctrico (EFI-DR-SFG) para estudiar la distribución de campo eléctrico en diodos orgánicos multicapa emisores de luz (OLEDs). Se observaron correlaciones notables entre el incremento de señal DR-SFG y el voltaje aplicado. Las señales SFG atribuibles al 4,4'-bis[N-(1-naftil-N-fenilamino)-bifenil] se incrementaron significativamente por la aplicación de un voltaje directo, mientras que la señal de aquellas de Alq₃ se incrementaron por la aplicación de un voltaje inverso. El fuerte incremento de la intensidad EFI-DR-SFG permite sondear, de forma no destructiva, la distribución del campo eléctrico local en la capa orgánica que contiene el OLED.

http://dx.doi.org/10.1063/1.4746273