CN100369293C

CN100369293C - Method for blocking hole in organic layer of organic semiconductor device

Info

Publication number: CN100369293C
Application number: CNB200510023306XA
Authority: CN
Inventors: 侯晓远; 王子君; 丁训民
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2005-01-13
Filing date: 2005-01-13
Publication date: 2008-02-13
Anticipated expiration: 2025-01-13
Also published as: CN1645643A

Abstract

The present invention relates to a method for blocking holes in an organic layer of an organic semiconductor device. In general, two basic processes are adjusted, controlled and influenced by selecting different electrodes to come in contact with an organic semiconductor, namely that the injection rate and the corresponding proportion of electrons or holes are influenced. Consequently, the luminous efficiency of an electronic luminous device and the area position of recombination luminescence are influenced. The present invention adulterates aluminium in a 1 nm to 10 nm of thin area of the organic semiconductor; the adulterating concentration, the molar ratio of the aluminum to an organic molecule, is from 0.1: 1 to 10: 1. Because the aluminium is adulterated, the luminescence of the device can be used for sensitively detecting whether the holes are completely blocked or not. Organic electroluminescence originates from the combination of the electrons and the holes in a luminous area. After the aluminium is adulterated in the thin area (far away from a luminous position for eliminating the influence of metal quenching) of one side of a hole transport area outside the luminous area, the device has not electroluminescence, which illustrates that the holes are completely blocked in the area where the aluminium is adulterated; an experiment indicates that in different NPB and Alq with organic semiconductor material, the operation of adulterating the aluminium can completely block the transmission of the holes.

Description

A kind of in the organic layer of organic semiconductor device the method for blocking hole

Technical field

The present invention relates to the organic luminescent device field, the method for blocking hole in the organic layer of concrete is a kind of organic semiconductor device.

Background technology

At present, device research based on organic semiconducting materials is in the ascendant, organic solar batteries from energy field, the organic electroluminescence device that shows the video picture field to information, and all obtained sufficient displaying to the various functional components and parts of the imitation traditional inorganic semiconductor relevant (except electricity injects organic semiconductor laser diode do not realize) with modern microelectronics, embodied powerful growth momentum of organic semiconductor and huge application potential.All these all directly relate to and are decided by the transmission course of two kinds of charged carriers, i.e. the transmission course in electronics and hole based on many character of organic semi-conductor functional device.If the transport behavior for charge carrier can effectively be regulated and control, just had the effective technical means design and produced the organic semiconductor device of particular characteristic.Organic electroluminescence device, exactly organic semiconductor thin-film is clipped between two electrodes with suitable work function, under forward bias, electronics and cavity energy are injected into effectively and form the exciton recombination luminescence in the organic semiconductor thin-film simultaneously, and its typical structure as shown in Figure 1.This organic semiconductor device structure can be passed through its luminosity, indicates some situation that its charge carrier transmits in semiconductive thin film sensitively, is the device architecture of carrier transport behavior in a kind of effective research organic semiconductor.In fact near the effect (aluminium of thin zone and debita spissitudo mixes by assigned address) of the complete blocking hole of organic semi-conductor any given position, the research that improves the luminous efficiency of device does not appear in the newspapers so far as yet.

Summary of the invention

The objective of the invention is to obtain a kind of technology easy, do not increase cost, improve the method for blocking hole in the organic layer of organic semiconductor device of device luminous efficiency, thereby effectively improve the luminous efficiency of device.

The present invention proposes a kind of in the organic layer of organic semiconductor device the method for blocking hole, be in organic layer as the NPB of hole transmission layer with to carry out thickness as the arbitrary position among the Alq of luminescent layer be that 1-10nm aluminium mixes, doping content is an aluminium to the mol ratio of organic molecule is 0.1: 1～10: 1.

The application of organic semiconductor device in organic semiconductor electronics and opto-electronic device that the present invention obtains.

The mix transmission effects of complete blocking hole of the aluminium in the thin zone in the organic semiconductor of the present invention, can be applied in general the organic semiconductor electronics and opto-electronic device, transmission by effective regulation and control hole, realize the organic semiconductor function element of special performance, perhaps realize the improvement of the organic semiconductor device performance relevant with hole transport.

Example one of the present invention and example two explanations, different organic semiconductors, for example Alq film and NPB film approach the aluminium doping transmission of blocking hole fully of the debita spissitudo in zone.Aluminium in the organic semiconductor thin-film mixes can also explain the J-V curvilinear characteristic to the hole barrier effect.For example, the J-V curve from Fig. 4 finds out that easily along with doping content improves gradually, the J-V curve then moved to the low pressure direction to the high pressure direction before this, and wherein the operating voltage of device 3# and 4# is also lower than the operating voltage of plain sample 1#.Operating voltage rising trend can work gradually owing to hole barrier, and hole current diminishes, and device voltage under same current density raises.Further raising along with doping content, hole barrier no longer is subject matter (substantially all stopping), the electron conduction increase becomes the principal element of decision operating voltage in the doped layer, aluminium is doped with the conduction that is beneficial to electronics, so the voltage drop of device 3# and 4# must be also lower than the voltage of the device 1# that undopes.And for example, the device of doping contents such as size such as among Fig. 2 three show along with doping position near ito anode, the J-V curve moves to the high pressure direction, illustrate that Al mixes the closer to anode, the hole that enters in the device is few more, the hole is blocked in outside the device more effectively, and the voltage at respective devices two ends uprises under the same current density.And the device that undopes is not owing to exist this hole barrier, so its J-V curve is in extreme lower position, under the promptly same current density, voltage is minimum.

The present invention also changes the aluminium negative electrode into the LiF/Al composite cathode, carried out the experimental study that is similar to, the aluminium that has also proved in the organic semiconductor thin-film thin regional debita spissitudo transmission of blocking hole equally fully of mixing, the selection of this effect and negative electrode is described, and it doesn't matter.

The easy easy realization of technology of the present invention, cost is not high, has improved the organic light-emitting device luminous efficiency greatly, by effective hole transmitting regulating and controlling, realizes having the semiconductor function device of special performance.

Description of drawings

Fig. 1 is the OLED structure schematic diagram.

Fig. 2 is four device architectures of making simultaneously and L-J-V curve chart, three device 2#, 3#, 4# aluminium doping molar ratio all is 1: 4, doping position is respectively the hole transmission layer 8nm near luminescent layer, the 8nm zone of the hole transmission layer NPB of the 8nm of hole transmission layer NPB central authorities and close anode ITO.Device 1# does not have doping.

Fig. 3 is four device architectures of making simultaneously and L-J-V curve chart, three device 2#, and 3#, 4# aluminium doping molar ratio was respectively 1: 3, and 1: 10 and 1: 12, doping position was that 1# the device that does not mix among the Alq near the 8nm of hole transmission layer NPB.

Fig. 4 is four device architectures of making simultaneously and L-J-V curve chart, three device 2#, and 3#, 4# aluminium doping molar ratio was respectively 1: 1, and 1: 2 and 1: 8, doping position was near among the 100nmAlq of negative electrode, the device 1# that does not mix to make performance comparison.

Fig. 5 is four device architectures of making simultaneously and L-J-V curve chart, three device 2#, and 3#, 4# aluminium doping molar ratio was respectively 1: 0.2, and 1: 1 and 1: 9, doping thickness all was 3nm, and doping position is the central authorities of 70nmAlq, and device 1# does not have doping.

Embodiment

Use in the experiment of Al doping blocking hole, the ITO substrate that the present invention buys commerce is handled through the conventional method ultrasonic cleaning and through UV ozone earlier, then imports the making of carrying out organic electroluminescence device in the vacuum chamber into.Under the same vacuum environment, same is designed on the good ITO substrate of photoetching, can make four samples that structure is different simultaneously, helps the performance comparison of different structure device like this.The sample for preparing directly imports the synchronism detection that carries out luminous-current density-voltage (L-J-V) curve the anhydrous and oxygen-free nitrogen glove box into from vacuum chamber.

Example one: in order to study the hole barrier effect that hole transmission layer Al mixes, the present invention is respectively in the thin zone of three diverse locations of hole transmission layer, the 6nm of central authorities, 6nm zone, both sides is carried out aluminium and is mixed, as shown in Figure 2, three aluminium doping devices all do not have electroluminescence, have shown simultaneously among the figure that the normal luminous device that does not have adulterated al is to contrast.The device that hole transmission layer aluminium mixes does not have electroluminescence, explanation successfully stops the transmission in hole fully in the aluminium doping in the thin zone of hole transmission layer, outstanding two aluminium doped region is away from the device of light-emitting zone, there is not the participation of the luminous exciton quenching effect of metal pair, the not luminous complete blocking effect that can only come from the hole at all.

Example two: the aluminium of present embodiment explanation Alq layer mixes to the hole barrier effect, mix at the Al that has carried out variable concentrations near the 8nm scope Alq zone of hole transmission layer, as shown in Figure 3, three doping devices give normal luminous not doping device simultaneously without any electroluminescence among the figure as a result.There are two kinds may cause three doping devices not luminous, first hole is successfully stopped by the aluminium doped region of Alq, it is luminous with electron recombination to move to adjacent not doped with Al q zone, it two is that Alq can not blocking hole move to not that doped region and electron recombination form exciton, but the adjacent metal zone falls (1 with the complete quencher of luminous exciton, 2), cause device not luminous.In order to test a kind of possibility in explanation back, the present invention has made the device of another structure, this moment, the 8nm scope Alq zone near hole transmission layer undoped, all the mix aluminium of variable concentrations of adjacent Alq (100nm), as shown in Figure 4, though because adjacent aluminium doped region increases with the aluminium doping content, the concentration quenching effect aggravation, but luminous complete quencher can not be fallen, the doping device of this key diagram 3 is not luminous is not because the concentration quenching of metal (aluminium) causes, but since the aluminium of Alq mix and the hole stopped fully cause.Because if can not stop fully, under enough big voltage, always have considerable hole and be transported to that doped with Al q layer and electron recombination are not luminous.

Example three: the present invention is with Al doping blocking hole effect in the organic semiconductor, be applied to do in the organic electroluminescence device of negative electrode with Al, by the hole being blocked in effectively in the light-emitting zone, realized the raising of device luminous efficiency to increase and the luminous probability of electron recombination.Because do the electroluminescent device of negative electrode with aluminium why low than the electroluminescent device efficient of making negative electrode with the littler lithium of work function, be because the less lithium cathode device of work function, the injection of electronics is more effective, make have enough electronics with from the anode injected holes at the light-emitting zone recombination luminescence, and make the device of negative electrode with the bigger aluminium of work function, because electron injection efficiency is low, feasible have the hole of quite a few not luminous with the electron recombination that negative electrode is come, directly flow to negative electrode on the contrary, form the hole leakage current, device just shows very poor luminous efficiency.Stop if will flow to the hole leakage current of negative electrode by a kind of way, be limited in the luminescent layer, just might improve the luminous efficiency of device.

Experimentally, mix, can contrast by experiment, find reasonable doping position for the Al of certain zone and ratio, both effectively with hole confinement in luminescent layer, reduce again because the negative effect of metal-doped quencher light-emitting zone exciton.Then at this doping position preferably, by regulating the doping ratio,, guarantee again simultaneously effectively hole barrier in light-emitting zone, thereby improve the luminous efficiency of device to reduce the quencher of the luminous exciton of aluminium atom pair.It is 32nm apart from the NPB layer that Fig. 5 has provided the doping position that the present invention's experiment gropes, doped region is three device architecture schematic diagrames of 3nm, sample 2# wherein, and the doping ratio of 3# and 4# was respectively 1: 0.2, (Alq: Al), sample 1# was the device that undopes in 1: 1 and 1: 9.From the J-L curve as can be seen, along with the doping ratio improves gradually, brightness increases gradually, to device 3# brightness maximum, the efficient of doping device 3# is also bigger than the efficient of the device 1# that do not mix, but along with doping content further improves, because the quencher of the luminous exciton of metal pair becomes significantly (2), device 4# brightness has dropped to lower than plain device.In a word, although existence exciton quencher to a certain degree, utilization aluminium doping blocking hole effect can effectively be improved the efficient of making the electroluminescent device of negative electrode with Al.

Claims

1. the method for a blocking hole in the organic layer of organic semiconductor device, it is characterized in that in organic layer as the NPB of hole transmission layer and to carry out thickness as the arbitrary position among the Alq of luminescent layer be that 1-10nm aluminium mixes, doping content is an aluminium to the mol ratio of organic molecule is 0.1: 1～10: 1.

2. the application of organic semiconductor device in organic semiconductor electronics and opto-electronic device of method acquisition according to claim 1.