浴铜灵有机分子材料对钙钛矿薄膜表面的钝化作用

采用2,9-二甲基-4,7-二苯基-1,10-邻二氮杂菲(浴铜灵,缩写:BCP)有机小分子作为钙钛矿薄膜与电子传输层之间的界面修饰层,从而使得反型结构的钙钛矿太阳电池性能得到显著改善。通过扫描电子显微镜研究发现:BCP分子可在钙钛矿薄膜样品表面的晶界间充分填充,推测其抑制了界面缺陷态的产生。进一步研究器件内部界面电荷的累积,并结合交流阻抗谱的分析,证实经BCP钝化的钙钛矿太阳电池中界面电荷的累积减少,光生载流子的复合被抑制,电池的光电转换效率由原来的15.7%提升到了17.4%。     

Effect of BCP ultrathin layer on the performance of organic light-emitting devices

Based on conventional double layer device, triple layer organic light-emitting diodes （OLEDs） with two heterostructures of indium-tin oxide （ITO）/N,N＇-diphenyl-N,N＇-bis（1-naphthyl）（1,1 ＇-biphenyl）-4,4＇-diamine（NPB）/2,9-dimethyl-4,7-diphenyl- 1,10-phenanthroline （BCP）/8-Hydroxyquinoline aluminum （Alq3）/Mg：Ag USing vacuum deposition method have been fabricated. The influence of different film thickness of BCP layer on the performance of OLEDs has been investigated. The results showed that when the thickness of the BCP layer film gradually varied from 0.1 nm to 4.0 nm, the electroluminescence （EL） spectra of the OLEDs shifted from green to greenish-blue to blue, and the BCP layer acted as the recombination region of charge carriers related to EL spectrum, enhancing the brightness and power efficiency. The power efficiency of OLEDs reached as high as 7.3 lm/W.     

Improved current efficiency in organic light-emitting devices with a hole blocking layer

A hole-blocking layer (HBL) of 4,7-diphenyl-1,10-phenanthroline (BPhen) is incorporated between the emitting layer (EML) and the electron transport layer (ETL) for a tris-(8-hydroxyqunoline)aluminum based organic light-emitting device (OLED). Such a structure helps to reduce the hole-leakage to the cathode, resulting in an improved current effi-ciency. The BPhen improves the balance of hole and electron injections. The current efficiency is improved compared with that of the device without the blocking layer. The highest luminous efficiency of the device with 6 nm BPhen acting as a blocking layer is 3.44 cd/A at 8 V, which is improved by nearly 1.5 times as compared with that of the de-vice without it.     

Structure optimization of organic light-emitting devices

A triple layer organic light-emitting diode (OLED) with two heterostructure of indium-tin oxide (ITO)/N,N’-diphenyl-N, N’-bis(1-naphthyl) (1,1’-biphenyl)-4,4’-diamine (NPB)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/ 8-Hydrox- yquinoline aluminum (Alq3)/Mg:Ag has been fabricated by using the vacuum deposition method. The influence of different film thickness of BCP layer on the performance of the OLEDs has been investigated. The results show that when the thickness of the BCP layer film gradually r...     

Novel cathode buffer layer of Ag-doped bathocuproine for small molecule organic solar cell with inverted structure

2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (C₂₆H₂₀N₂), known as bathocuproine (BCP), is a commonly used cathode buffer layer in conventional structure organic solar cells (OSCs). We demonstrated that BCP layer can also be used as a buffer layer in inverted structure OSCs. Unfortunately, the device exhibited an anomalous kink in the current density–voltage (J–V) characteristics, namely, an S-shaped J–V curve, leading to a low fill factor and low power conversion efficiency (PCE). To improve device performance, Ag-doped BCP layer (Ag:BCP) was used to replace the BCP layer. The results showed that the Ag:BCP layer can eliminate the S-kink in the J–V curve, resulting in a large improvement of fill factor and PCE. The origin of the S-shaped J–V curve was demonstrated to originate from the charge accumulation at the fullerene (C₆₀)/BCP interface. On the contrary, the C₆₀/Ag:BCP interface has favorable electronic properties with beneficial gap states for the transport of free carriers. Together with the good conductivity of Ag:BCP layer and the smooth morphology properties, the device performance was greatly improved by Ag:BCP buffer layer.     

BCP增透膜对顶发射器件发光性能的影响

制作了基于有机材料2,9-二甲基4,7-二苯基-9,10-菲咯啉（BCP）作增透膜的硅基顶发射有机电致发光器件,探讨了BCP增透膜对于器件亮度、效率等光学参数的改善以及对于器件光谱的影响,并结合微腔理论和转移矩阵理论进行了计算,验证了理论与实验结果的一致性。     

Enhancement of electron injection in inverted bottom-emitting organic light-emitting diodes using Al/LiF compound thin film

The inverted bottom-emitting organic light-emitting devices (IBOLEDs) were prepared, with the structure of ITO/Al (x nm)/LiF (1 nm)/Bphen (40 nm)/CBP: GIr1 (14%):R-4b (2%) (10 nm)/BCP (3 nm)/CBP:GIr1 (14%):R-4b (2%) (20 nm)/TCTA (10 nm)/NPB (40 nm)/MoO3 (40 nm)/Al (100 nm), where the thickness of electron injection layer Al (x) are 0 nm, 2 nm, 3 nm, 4 nm and 5 nm, respectively. In this paper, the electron injection condition and luminance properties of inverted devices were investigated by changing the thickness of Al layer in Al/LiF compound thin film. It turns out that the introduction of Al layer can improve electron injection of the devices dramatically. Furthermore, the device exerts lower driving voltage and higher current efficiency when the thickness of electron injection Al layer is 3 nm. For example, the current efficiency of the device with 3-nm-thick Al layer reaches 19.75 cd·A^-1 when driving voltage is 7 V, which is 1.24, 1.17 and 17.03 times larger than those of the devices with 2 nm, 4 nm and 5 nm Al layer, respectively. The device property reaches up to the level of corresponding conventional device. In addition, all inverted devices with electron injection Al layer show superior stability of color coordinate due to the adoption of co-evaporation emitting layer and BCP spacer-layer, and the color coordinate of the inverted device with 3-nm-thick Al layer only changes from (0.580 6, 0.405 6) to (0.532 8, 0.436 3) when driving voltage increases from 6 V to 10 V.     

白光有机电致发光器件发光稳定性研究

基于红绿/蓝双发光层,制作了结构为ITO/MoO ₃(10nm)/NPB(40nm)/TCTA(10nm)/CBP:R-4B(2%):GIR1(14%,X nm)/mCP:Firpic(8%,Y nm/BCP(10nm)/Alq₃(40nm)/LiF(1nm)/Al( 100nm)的白色全磷光有机电致发光器件(OLED),通过 调节红绿发光层的厚度X与蓝光发光层的厚度Y,研究了不同发光层厚度器件发 光性能的影响。研究发现:当X 为23nm、Y为7nm时,器件的光效和色坐标都具有 很高的稳定性,在电压分别为5、 10和15V时,色坐标分别为(0.33,0.37)、(0.33,0. 37)和(0.34,0.38);在电压为 5V时,电流密度为0.674mA,亮度为158.7cd ,最大电流效率为26.87cd/A;利用电子阻 挡材料TCTA和空穴阻挡材料BCP能够显著提高载流子的复合效率。分析认为:发光层顺序 为红绿/蓝时,更有利于蓝光的出射,从而使白光的色坐标更稳定。     

BCP层对蓝光有机电致发光器件效率的影响

采用真空热沉积的方法,在常规的三层器件基础上,通过改变空穴阻挡层BCP的厚度,制备了具有结构为氧化铟锡(ITO)/N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'-diamine(NPB)/2,9-dimethyl-4,7-diphenyl-1,10-phenan throline(BCP)/Hydroxyquinoline aluminum(Alq3)/Mg:Ag的双异质结的有机电致发光器件.结果表明,当空穴阻挡层BCP的厚度从0.1 nm逐渐增加到4.0 nm时,器件的电致发光光谱实现了从绿色到蓝绿色再到蓝色发射的转变.同时,空穴阻挡层BCP起到了调节载流子复合区域和改变器件发光颜色的作用,并且通过详细的器件结构优化证明一定厚度的BCP层显著地提高了蓝光器件的效率,达到了7.3 lm/W.     

Improving the performance of organic light-emitting diodes containing BCP/LiF/Al by thermal annealing

In this paper, we examined the effect of post-packaging annealing on the performance of organic light-emitting diodes containing tris-(8-hydroxyquinoline) aluminum (Alq,) or 2,9-Dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) in direct contact with a LiF-Al bilayer cathode. The detailed electroluminescent (EL) characteristics were compared before and after annealing at 70 /spl deg/C for 5 hrs. It was found that better luminous efficiency as well as greater power efficiency could be achieved for devices with BCP/LiF/Al structure. However, other devices consisting of Alq/sub 3//LiF/Al were less affected. It is believed that the thermal treatment helps to enhance the electron injection for the former, and less helpful for the latter.     

Tandem white organic light-emitting device using non-modified Ag layer as cathode and interconnecting layer

Tandem white organic light-emitting device (WOLED) using non-modified Ag film as cathode and interconnecting layer is demonstrated. Effective electron injection is achieved when Ag is deposited on 4,7-diphenyl-1,10-phenanthroline electron transporting layer without any modified layer. Single OLED with Ag cathode shows comparable performance to that of device with Mg:Ag cathode. Such tandem WOLED exhibits low driving voltage, high power efficiency (15.1 lm/W at 1000 cd/m²) and low efficiency roll-off. The working mechanisms of single and tandem devices were discussed in detail. These results could provide a simple method to fabricate high performance tandem white OLED.     

Blue top-emitting organic light-emitting devices using a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline outcoupling layer

We fabricate a blue top-emitting organic light-emitting device (TEOLED) based on 4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl. Different from the conventional TEOLEDs that use ITO as a thickness adjustment layer to make the cavity length matchable with the resonant wavelength of the blue light, we construct the blue emission TEOLED through suppressing multiple-beam interference and utilizing wide-angle interference to enhance the blue emission. With a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline light outcoupling layer to reduce the reflectivity of the Sm/Ag cathode, the blue emission can be obtained and its chromaticity is comparative to that from a bottom-emitting OLED. In addition, the blue emission shows stable spectra when the viewing angle alters from 0° to 75°.     

Efficient organic near-infrared photodetectors based on lead phthalocyanine/C60 heterojunction

High efficiency organic small molecule near-infrared photodetectors (NIR-PDs) based on a lead phthalocyanine/C₆₀ planar heterojunction are demonstrated. The NIR-PDs show a broad-band response that extends to 1100 nm. The performance of the NIR-PDs is improved by using CuI as anode buffer layer. The optimized NIR-PD exhibits a response peak at about 900 nm with external quantum efficiencies (EQEs) of 19.7% at zero bias and 35.1% at −6 V, which are higher than other small molecule NIR-PDs reported. Comparable EQEs of 18.0% at zero bias and 33.2% at −6 V are found in the NIR-PD by further using 4,7-diphenyl-1,10-phenanthroline as cathode buffer layer. Meanwhile, the dark current is significantly reduced, which results in a high detectivity of 2.34 × 10¹¹ Jones at zero bias, which is among the highest detectivities reported for organic small-molecule NIR-PDs. Besides, the NIR-PDs show a reliable stability in ambient condition.     

CBP超薄层对有机电致磷光器件效率的影响

在空穴传输层(HTL)和发光层(EML)间插入4,4-N,N′-二咔唑基联苯(CBP)超薄层,制备了结构为ITO/NPB/CBP(xnm)/CBP:Ir(ppy)3/BCP/Alq3/LiF/Al有机电致磷光器件。与未插入CBP超薄层的器件相比,CBP超薄层的引入可以有效阻挡Ir(ppy)3的三线态能量通过Dexter能量转移到HTL的NPB中,减少无辐射能量损失,提高了器件发光效率。调整CBP薄层的厚度,当x为3nm时,器件的效率提高幅度最大,从x为0nm时的9.0cd/A提高到16.9cd/A。     

Effect of lithium and silver diffusion in single-stack and tandem OLED devices

A study of metal (Li, Ag) diffusion has been carried out in an archetypal OLED device based on N,N′-di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine|tris(8-hydroxyquinolinato) aluminum|4,7-diphenyl-1,10-phenanthroline (NPB|Alq₃|Bphen). Using single-stack and two-stack tandem OLED structures with variations of layer thicknesses and metal layer placements, we have found that Ag vapor-deposited on Alq₃ layer can diffuse or penetrate deep into Alq₃, up to ∼2,000 Å, causing luminescence quenching. This diffusion can be substantially prevented by a thin layer of Li or Bphen deposited on Alq₃ prior to the deposition of Ag. In contrast, Li diffusion in either Alq₃ or Bphen is limited to about 50–100 Å. Li appears to be able to diffuse into Bphen irrespective of the order of Li and Bphen depositions.     

Efficient inverted polymer solar cells incorporating doped organic electron transporting layer

An efficient inverted polymer solar cell is enabled by incorporating an n-type doped wide-gap organic electron transporting layer (ETL) between the indium tin oxide cathode and the photoactive layer for electron extraction. The ETL is formed by a thermal-deposited cesium carbonate-doped 4,7-diphenyl-1,10-phenanthroline (Cs₂CO₃:BPhen) layer. The cell response parameters critically depended on the doping concentration and film thickness of the Cs₂CO₃:BPhen ETL. Inverted polymer solar cell with an optimized Cs₂CO₃:BPhen ETL exhibits a power conversion efficiency of 4.12% as compared to 1.34% for the device with a pristine BPhen ETL. The enhanced performance in the inverted device is associated with the favorable energy level alignment between Cs₂CO₃:BPhen and the electron-acceptor material, as well as increased conductivity in the doped organic ETL for electron extraction. The method reported here provides a facile approach to optimize the performance of inverted polymer solar cells in terms of easy control of film morphology, chemical composition, conductivity at low processing temperature, as well as compatibility with fabrication on flexible substrates.     

Thermally stable inverted organic light-emitting diodes using Ag-doped 4,7-diphenyl-1,10-phenanthroline as an electron injection layer

The thermal stability of organic functional materials affects the performance and lifetime of organic light-emitting diodes (OLEDs). We have developed a thermally stable inverted OLEDs (IOLEDs) by employing silver (Ag) doped into 4,7-diphenyl-1,10-phenanthroline (Bphen) as an n-type doped electron injection layer (EIL). We found that the formation of Ag complexes by coordination reaction could enhance the thermal stability and produce an asymmetric diffraction pattern based on an analysis of grazing incidence small angle X-ray scattering. Interestingly, with the annealing temperature increasing to 100 °C, the electrical properties of electron-only cells show differentiated phenomenon that the current density based on Ag dopant remains basically unchanged, which is opposite to Cs₂CO₃ dopant. In addition, at the high temperature of 100 °C, the IOLEDs with Cs₂CO₃ doped Bphen as an EIL was damaged completely, while the Ag dopant-based devices still maintained good photoelectrical characteristics. Finally, we have demonstrated that the optimized IOLEDs achieved a 40.3% enhancement in current efficiency compared to the conventional device. This work provides a new strategy to increase the thermal stability and performance for the application of IOLEDs operated under high temperature.     

基于混合配体Znq(DBM)的单色和白色OLED

以8-羟基喹啉(q)和1,3-二苯基-1,3-丙二酮定向合成了有机小分子配合物Znq(DBM),将其作为发光层制备了单色有机电致发光器件(OLED)。在结构为ITO/m-MTDATA(5nm)/NPB(40nm)/Znq(DBM)(60nm)/LiF(0.5nm)/Al(100nm)的器件中,启亮电压为5V,最大亮度达到4 575cd/m2。同时又在器件中引入间隔层BCP,研究其不同厚度对OLED性能的影响。在结构为ITO/m-MTDATA(5nm)/NPB(40nm)/BCP(x nm)/Znq(DBM)(60nm)/LiF(0.5nm)/Al(100nm)的器件中,当BCP层厚为0nm时,发光颜色为黄绿色;当BCP层厚为1nm时,发光颜色为白色,色坐标为(0.29,0.33),最大亮度为2 231cd/m2;当BCP层厚为5nm时,发光颜色为蓝色。根据器件结构和性能,讨论了其内部机理。     

High-efficiency and multi-function blue fluorescent material for organic electroluminescent devices

We demonstrate one high-efficiency blue fluorescent material, N-(4-((E)-2-(6-((E)-4-(diphenylamino)styryl)naphthalen-2-yl)vinyl)phenyl)-N-phenylbenzenamine, with an emissive peak of 472 nm and the hole-transporting property speculated from different devices. It can function either as the single emissive layer or as the dye doped in N,N′-dicarbazolyl-4-4′-biphenyl (CBP). The former shows a maximum current efficiency and luminance of 7.06 cd/A (0.04 mA/cm²) and 16 930 cd/m², in contrast to 11.5 cd/A (4.35 mA/cm²) and 25 690 cd/m² for the latter. The better performance of the latter can be attributed to the bipolar carrier transport property of CBP and the hole-blocking and electron-transporting characteristic of 4,7-diphenyl-1,10-phenanthroline (BPhen), which resulting in a good balance of holes and electrons. Moreover, the Commission Internationale De L’Eclairage coordinates of the latter change slightly from (0.162, 0.3) to (0.148, 0.268) upon increasing the voltage from 3 V to 14 V.