【作者】 代千；

【导师】 张希清；

【作者基本信息】 北京交通大学 ， 光学， 2012， 博士

【摘要】 紫外光探测器已经广泛应用于天体物理分析,大气臭氧研究,环境污染监测,火灾预警,矿产勘探和开采,医疗卫生、紫外通信以及导弹预警等领域。有机紫外光探测器由于具有制造成本低、工艺简单,可大面积和柔性衬底生产等优点,因而备受国内外学者关注。但目前有机紫外光探测器由于入射电极ITO在短波长的强烈吸收,使得深紫外光探测器的研究受到了限制,而且其光响应度和探测率等光电性能还有待进一步的提高。本论文针对上述不足,以常见的宽禁带有机小分子半导体材料为基础,选用了短波长的透光性能和导电性能很好的PEDOT:PSS作为入射电极,制备了各种不同结构的有机紫外光探测器,研制出了高性能的深紫外光探测器和可见盲型探测器。并且通过优化器件结构,提高了激子的分离、载流子的传输以及电极对电荷的收集,改善了器件的光电性能。主要研究工作如下：1.制备出双层的NPB/BND异质结型和单层的NPB:BND体异质结型紫外光探测器。研究了不同给体和受体厚度对于器件的光电流密度的影响,并且分析了给体材料和受体材料之间的界面修饰对于器件的激子分离效率的影响。2.结合双层异质结和单层体异质结两种结构器件优点,研制出NPB/NPB:BND/BND结构紫外光探测器。研究了给体和受体材料的混合薄层对器件的光电流密度和光响应度等性能的影响。加入混合薄层的器件既增加了给体和受体材料之间的接触面积,提高了激子分离效率,又保留了较强的载流子传输能力,加强了电极对电荷的收集,减少了载流子的再度复合。器件在365nm的紫外光照射下,-3V时得到的光电流密度为32.61μA/cm2,光响应度为30.3mA/W。3.制备出了高性能的NPB/PBD紫外光探测器,研究了给体和受体厚度对器件光响应度的影响,讨论了给体和受体材料之间的能级匹配对于光生激子的分离效率的影响。器件在波长为350nm,光功率密度为60μW/cm2的紫外光照射下的光响应度高达630mA/W。4.选用高电导率聚合物PEDOT:PSS作透明入射电极,研制出高性能的石英/PEDOT:PSS(PH1000)/PEDOT:PSS(P VP4083)/NPB/Bphen/LiF/Al结构深紫外光探测器。通过添加DMSO和异丙醇等材料,改善了PEDOT:PSS电极的薄膜质量和导电性能。同时研究了以PEDOT:PSS(P VP4083)作为阳极修饰材料对于电极的空穴收集能力以及器件的临界击穿电压的影响。该器件在220nm的紫外光照射下,在反向电压为7.5V时,得到了77μA/cm2的光电流密度,502mA/W的光响应度和2.67×1012cmHz1/2/W的探测率。5.选用在可见光区没有吸收的给体材料TAPC替代NPB,研制出了TAPC/Bphen和TAPC/TAPC:Bphen两种可见盲型深紫外光探测器。两个器件在-12V时的暗电流密度分别为0.024和0.87μA/cm2,光电流密度为34和56μA/cm2,光响应度为52和75mA/W。其中TAPC/TAPC:Bphen器件的光电流密度和光响应度要稍好于TAPC/Bphen器件,但由于暗电流密度较大,其信噪比反而降低了。为了使器件的电子传输能力提高到与器件的空穴传输能力相匹配,从而降低载流子再度复合的几率,制备出了高性能的TAPC/TAPC:Bphen/Bphen:Cs2CO3结构可见盲型深紫外光探测器,器件的暗电流密度降低到0.026μA/cm2,而光电流密度提高到106μA/cm2,光响应度提高到126mA/W。更多还原

【Abstract】 Ultraviolet (UV) photodetectors (PDs) have wide applications in astrophysical analysis, the atmospheric ozone research, environmental pollution monitoring, fire alarm, mineral exploration and mining, health care, as well as military science and other fields. Wide band gap organic UV PDs have much more attractive to scholars, due to the advantages of low manufacturing cost, simple process and ease of production on large area or flexional substrates. However, the detection of deep-UV light has been limited cause the strong absorption in the short wavelength of the incident electrode ITO of organic UV PDs. Moreover, the responsivity and detectivity of organic UV PDs remains to be further improved.In this work, we used common wide band gap organic small molecule semiconductor materials to prepared different structures of organic UV PDs to improve these shortcomings above, based on the incident electrode PEDOT:PSS with good short-wavelength light transmission properties and electrical conductivity. We also developed high-performance deep-UV PDs detector and visible-blind UV PDs. By optimizing structure of the devices to improve the exciton separation, carrier transportation and charge collection of the electrodes, the optical and electrical properties of organic UV PDs were enhanced. The main research works are as follows:1. A double layer heterojunction device and a single layer bulk heterojunction device based on NPB and BND as donor and acceptor materials were prepared to analyze the impact of the interface between donor and acceptor. The photocurrent density of the devices with a different donor and acceptor thickness and exciton separation efficiency of the devices with modification of the interface between donor and acceptor were discussed.2. Combined advantages of double layer heterojunction and bulk heterojunction, we developed the NPB/NPB:BND/BND device by adding a blend layer of NPB and BND between the separate NPB and BND film. The impact of blend thin layer of donor and acceptor to the performance of the device was discussed. The revised organic UV PD was shown a photocurrent density of32.61μA/cm2and a responsivity of30.3mA/W at365nm with-3V bias.3. A high performance NPB/PBD UV PDs was prepared to study the photocurrent density with different thickness of donor and acceptor and the separation efficiency of photoinduced exciton by improved energy level matching between donor and acceptor. The device was shown a responsivity of630mA/W at-3V with350nm light of60mW/cm2light power density, which is better than the results reported in the literature.4. We proposed that using the high conductivity polymer PEDOT:PSS(PH1000) to form a transparent electrode to replace ITO conductive glass as the incident anode, and developed a high-performance quartz/PEDOT:PSS(PH1000)/PEDOT:PSS(P VP4083)/NPB/Bphen/LiF/Al structure deep-UV PD. By adding materials such as DMSO and isopropyl alcohol, the quality of the film and conductive properties of PEDOT:PSS electrode were improved. PEDOT:PSS(P VP4083) improved the holes gathering capabilities and the critical breakdown voltage of the device as a modified material for the anode. The device was shown a photocurrent density of771μA/cm2and a responsivity of502mA/W and a detectivity of2.67×1012cmHz1/2/W at-7.5V with a220nm UV light.5. Due to the TAPC film had no absorption to visible light, we developed the TAPC/Bphen and TAPC/TAPC:Bphen two kinds of visible-blind deep-UV PDs used TAPC to replace NPB as the donor. The devices were shown dark current density of0.024and0.87μA/cm2, photocurrent density of34and56μA/cm2and responsivity of52and75mA/W. The photocurrent density of TAPC/TAPC:Bphen device was better than the TAPC/Bphen device, but the dark current density was reduced so that the signal to noise ratio to be much lower. In order to improve the ability of the electron transport ability of the device to matching the hole transport ability, we prepared a high-performance TAPC/TAPC:Bphen/Bphen:Cs2CO3structure visible-blind deep-UV PD. The dark current density was reduced to0.026μA/cm2, the photocurrent density was increased to106μA/cm2and the responsivity was increased to126mA/W.更多还原