Absorption (dotted lines), photo- (dashed lines), and electroluminescence (solid lines) spectra for (A), (B), and (C) diameter QDs covered by of . Voltages and currents are (A) , ; (B) , ; and (C) , , respectively. Schematic of the structure of the multilayered QD LEDs is shown in the inset.
Energy level diagram of the multilayered QD LEDs.
Current-voltage curves of the QD LEDs with an average dot size of (solid line), (dashed line), and (dotted line). Triangles , circles , and solid squares represent the forward bias dependence of the electroluminescence intensity in the three samples. The electroluminescence spectra of the QD LEDs with a dot size of are shown as a function of the bias in the inset. The biases for the electroluminescence in the inset are 5.0 (dashed line) and (solid line).
Current-voltage characteristics for several QD LEDs with the QDs and the TPD (dotted lines) and the devices of only the TPD without the QDs (solid line) or only the QDs without the TPD (dashed lines). Inset: Electroluminescence spectra of the QD LEDs with (solid line) and without the hole conductor TPD (dotted line) under forward voltages of 5.0 and .
Electroluminescence spectra of the QD LEDs with different concentrations of the QDs. The resulting interface coverages for samples A–D were estimated to be 0.3, 0.2, 0.1, and of the QDs, respectively. No QDs were incorporated into the TPD in sample E. The spectra were taken under low voltage of about .
Absorption (dotted lines) and electroluminescence (dashed-dotted lines) spectra of the QDs with the TOPO (A), dodecylamine (B), and polymer (C) ligands at forward biases of 5.0, 5.5, and , respectively. The solid and dashed lines represent the photoluminescence spectra from the QDs in the LEDs and from a thin film of the same QDs on a thin glass substrate, respectively.
Article metrics loading...
Full text loading...