No abstract

The mechanisms for energy transfer including Förster resonance energy transfer (FRET) and radiative energy transfer in ternary-emissive system consists of blended-quantum dots (QDs, red-QDs blended with blue-QDs) emissive layer (EML) and blue-emissive hole-transport material that contained in quantum dot light-emitting diodes (QLEDs) are complicated. As the energy transfer could exhibit either positive or negative impact on QD’s photoluminescence (PL) and electroluminescence (EL), it is important to analyze and modulate energy transfer in such ternary-emissive system to obtain high-efficiency QLEDs. In this work, we have demonstrated that proper B-QDs doping has a positive impact on R-QDs’ PL and EL, where these improvements were attributed to the B-QDs’ spacing effect on R-QDs which weakens homogeneous FRET among R-QDs and near 100% efficient heterogeneous FRET from B-QDs to R-QDs. With optimization based on the analysis of energy transfer, the PL quantum yield of blended-QDs (with R:B blending ratio of 90:10, in quality) film has been enhanced by 35% compared with that of unblended R-QDs film. Moreover, thanks to the spacing effect and high-efficiency FRET from B-QDs to R-QDs, the external quantum efficiency of QLEDs that integrate optimized blended-QDs (R:B=90:10) EML reaches 22.1%, which is 15% higher than that of the control sample (19.2%) with unblended R-QDs EML. This work provides a systematically analytical method to study the energy transfer in ternary-emissive system, and gives a valid reference for the analysis and development of the emerging QLEDs that with blended-QDs EML.

Estimation method of mixing ratio of materials in processed foods by amino acid patterns were invented by Tamura (the traditional way). It shows the ratio of buckwheat protein in dried buckwheat noodles as follows : (A) is the ratio of buckwheat protein. and are the amounts of amino acids of buckwheat, flour, and a sample, respectively. The summation of and is standardized to. In short, the equation (A) is not estimating the mixing ratio of buckwheat as weight ratio in dried buckwheat noodles, but gives "protein" ratio. We devised the estimation method of the mixing ratio of buckwheat as weight ratio (the improved way). The equation is as follows : (B) and are the average amounts of amino acids of buckwheat and flour. and are the amounts of the protein of buckwheat, flour, and a sample defined as and respectively. The equation (B) could estimate the mixing ratio of buckwheat as weight ratio, not protein ratio. Then, a lot of dried buckwheat noodles contain vital gluten. We devised the estimation method of the mixing ratio of buckwheat in such noodles (three materials system). The equations are as follows : (C) (D) (E) and are the mixing ratio of buckwheat and vital gluten, and is the average amount of amino acids of vital gluten. By this method, the mixing ratio of buckwheat was estimated within the standard deviation of .