基于铱配合物有机光电子器件的研究
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摘要
由于金属铱配合物的重原子效应,使得有机磷光器件能获得100%的理论内量子效率。所以自1998年首个磷光电致发光器件问世以来,铱配合物的磷光器件一直是人们研究的热点。由于磷光材料有长的激子扩散长度,近年来也用来提高光伏器件的性能。本文以金属铱配合物为核心材料,对有机光电子器件(有机电致发光器件以及光伏器件)的器件物理进行了一系列研究。
以Ir(ppy)_3为发光材料的高效率绿色磷光器件。利用CPB:Ir(ppy)_3为发射层,把原本只有一个复合区的发射层在劈裂层Bphen的作用下,变成了两个复合区。通过调节Bphen的厚度和位置,调节两个复合区的载流子分布以及激子分布。这种结构一方面增加载流子形成激子的几率,另一方面减少载流子-激子的猝灭。同时,超薄Bphen层还对空穴的传输起到一定阻挡作用,平衡了载流子注入,提高了器件的性能。
研究了以短三重态寿命的磷光材料IrPi为发光材料的绿光器件。采用了多复合发射区的结构制作了高效率OLED器件,器件最高外量子效率达到了18.6%,同时器件的三重态-三重态猝灭也得到控制。
研究了几个新型的红色、橙色磷光材料:Ir(stybt)2acac、Ir(stybt)2ba、Ir(Meo-stybt)_2acac、Ir(MeO-stybt)_2ba、IrC_6的光物理性能以及电致发光性质。并把这些材料应用到有机光伏器件当中,深入研究了其在光伏器件里面的物理机制。由于掺杂剂的加入,对增加了器件在可见光部分的光吸收,Ir(stybt)2acac吸收的能量能够比较好地传递给C_(60);同时在CuPc/C_(60): Ir(stybt)_2acac结构里,形成了两个光电池系统,载流子能进行更好的分解。这个器件的最大短路电流达到9.46 mA/cm~2,能量转化效率达到2.46%。
A great deal of progresses have been made on obtaining high electroluminescence performances due to useing of both the singlet and triplet excitons, and a maximum internal efficiency of 100% in phosphorescence devices could be harvested. Since 1998, when the first phosphorescence device had been made, organic metal complexes have drawn much attention in organic electronics. In this work, organic optoelectronic devices, including organic light-emitting diodes (OLEDs) and organic photovoltaic (OPV) devices based on Ir-complex were prepared to investigate their device physics and improve their performances.
We demonstrated a considerable increase in current efficiency of fac-tris(2-phenylpyridine) iridium doped phosphorescent organic green-light emitting diode in which a thin 4,7 dipheny-1,10-phenanthroline (Bphen) layer acts as a cleaving layer. A maximum current efficiency of 53 cd/A was obtained, which was higher for 2.3 folds than that of the device without it. The efficiency improvement attributed to a higher exciton formation probability in the recombination zone and better balance of the carrier injection.
We made a high-efficiency electrophosphorescent device doped with bis(2-phenyl-benzoimidazole) iridium (III) acetylacetonate with a triplet lifetime in the range of nanoseconds. The doped mixed host was sandwiched by two doped single-host layers. Multi-recombination zones were formed in the emission layer. Such a structure could increase the proportion of recombined carriers to injected carriers and extend the recombination zone. As a result, a maximum external quantum efficiency of 18.6% was attained due to the presence of multi-recombination zones.
We demonstrated a enhanced power conversion efficiency (PCE) of a OPV by doping 4 wt % IrC_6 phosphor into C60 accepter layer in CuPc/C60 OPV diode, here IrC_6 is iridium(III) bis(3-(2-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-onato-N’,C4) (acetyl acetonate). The increase in PCE by doping IrC_6 was attributed to energy and/or electron transfers from IrC_6 to C60 species, presence of a IrC_6/ C60 sub-PV cell, as well the rising absorption of IrC_6 in the cell at 400-500 nm waveband. The Increase in PV response mainly came from the enhanced photocurrent density of the PV cell.
以Ir(ppy)_3为发光材料的高效率绿色磷光器件。利用CPB:Ir(ppy)_3为发射层,把原本只有一个复合区的发射层在劈裂层Bphen的作用下,变成了两个复合区。通过调节Bphen的厚度和位置,调节两个复合区的载流子分布以及激子分布。这种结构一方面增加载流子形成激子的几率,另一方面减少载流子-激子的猝灭。同时,超薄Bphen层还对空穴的传输起到一定阻挡作用,平衡了载流子注入,提高了器件的性能。
研究了以短三重态寿命的磷光材料IrPi为发光材料的绿光器件。采用了多复合发射区的结构制作了高效率OLED器件,器件最高外量子效率达到了18.6%,同时器件的三重态-三重态猝灭也得到控制。
研究了几个新型的红色、橙色磷光材料:Ir(stybt)2acac、Ir(stybt)2ba、Ir(Meo-stybt)_2acac、Ir(MeO-stybt)_2ba、IrC_6的光物理性能以及电致发光性质。并把这些材料应用到有机光伏器件当中,深入研究了其在光伏器件里面的物理机制。由于掺杂剂的加入,对增加了器件在可见光部分的光吸收,Ir(stybt)2acac吸收的能量能够比较好地传递给C_(60);同时在CuPc/C_(60): Ir(stybt)_2acac结构里,形成了两个光电池系统,载流子能进行更好的分解。这个器件的最大短路电流达到9.46 mA/cm~2,能量转化效率达到2.46%。
A great deal of progresses have been made on obtaining high electroluminescence performances due to useing of both the singlet and triplet excitons, and a maximum internal efficiency of 100% in phosphorescence devices could be harvested. Since 1998, when the first phosphorescence device had been made, organic metal complexes have drawn much attention in organic electronics. In this work, organic optoelectronic devices, including organic light-emitting diodes (OLEDs) and organic photovoltaic (OPV) devices based on Ir-complex were prepared to investigate their device physics and improve their performances.
We demonstrated a considerable increase in current efficiency of fac-tris(2-phenylpyridine) iridium doped phosphorescent organic green-light emitting diode in which a thin 4,7 dipheny-1,10-phenanthroline (Bphen) layer acts as a cleaving layer. A maximum current efficiency of 53 cd/A was obtained, which was higher for 2.3 folds than that of the device without it. The efficiency improvement attributed to a higher exciton formation probability in the recombination zone and better balance of the carrier injection.
We made a high-efficiency electrophosphorescent device doped with bis(2-phenyl-benzoimidazole) iridium (III) acetylacetonate with a triplet lifetime in the range of nanoseconds. The doped mixed host was sandwiched by two doped single-host layers. Multi-recombination zones were formed in the emission layer. Such a structure could increase the proportion of recombined carriers to injected carriers and extend the recombination zone. As a result, a maximum external quantum efficiency of 18.6% was attained due to the presence of multi-recombination zones.
We demonstrated a enhanced power conversion efficiency (PCE) of a OPV by doping 4 wt % IrC_6 phosphor into C60 accepter layer in CuPc/C60 OPV diode, here IrC_6 is iridium(III) bis(3-(2-benzothiazolyl)-7-(diethylamino)-2H-1-benzopyran-2-onato-N’,C4) (acetyl acetonate). The increase in PCE by doping IrC_6 was attributed to energy and/or electron transfers from IrC_6 to C60 species, presence of a IrC_6/ C60 sub-PV cell, as well the rising absorption of IrC_6 in the cell at 400-500 nm waveband. The Increase in PV response mainly came from the enhanced photocurrent density of the PV cell.
引文
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