高性能聚合物光电探测器的研究

发布时间：2018-05-05 16:05

本文选题：聚合物光电二极管探测器 + 溶剂蒸汽退火　；参考：《华南理工大学》2016年博士论文

【摘要】：基于光电二极管结构的聚合物光电探测器是一种捕获光信号并将之转化为电信号输出的器件。与无机光电探测器相比,聚合物光电探测器拥有许多独特的优势,比如质量轻、材料来源丰富、易大规模生产等,正受到越来越多的关注。从原理上看,聚合物光电探测器与有机/聚合物太阳电池的关系非常密切,两者有相同的器件结构,光电转化过程也相同。比探测率是光电探测器的一项关键性能指标。目前,越来越多比探测率超过10~(12)Jones的有机光电探测器见诸报道,表明有机光电探测器的关键性能指标可以和无机光电探测器媲美。要进一步提高聚合物光电探测器的性能,除了需要性能更加优异的新颖材料,还需要深入对其工作机理和调控要素进行深入研究。近几年的文献报道表明,作为一种技术手段,有机溶剂蒸汽退火(SVA)已经被证实可以有效调控有机/聚合物光活性层的微观形貌,有助于光生激子的拆分和电荷输运,从而抑制载流子复合,提升器件的短路电流。目前这种方法在有机/聚合物太阳电池领域已经应用非常广泛,但将之应用在聚合物光电探测器方面还鲜有报道。在第二章中,我们通过使用四氢呋喃溶剂对探测器活性层进行溶剂蒸汽退火处理的办法,调控PCDTBT:PC_(71)BM混合物薄膜的形貌,,成功将探测器的光响应度从90 mA/W提升到了185 mA/W,增幅超过100%,且避免了探测器的暗电流密度变大,最终将探测器的比探测率从1.86×10~(12)Jones增加到了5.94×10~(12)Jones。在论文的第三章,我们制备了基于PBDTTT-C-T:PC_(71)BM和倒置结构的聚合物光电探测器,并将之与正装结构的探测器相对比。实验表明,两种器件结构的外量子效率(EQE)相当,但倒置器件的暗电流密度较正装器件的要小2到3个数量级,因而倒置器件的比探测率大大优于常规的正装器件。在此基础上,我们实现了峰值比探测率达到1.58×10~(13) Jones聚合物光电探测器。除此之外,器件的开关比达到了10~5量级,频率响应达到17 MHz,线性动态区约为90 dB,具备优秀的综合性能。联系半导体/金属接触的能级理论,我们对器件的机理进行了分析,认为倒置结构中阳极界面MoO_3/Al与聚合物半导体之间具有更大的肖特基势垒是抑制暗电流密度的关键原因。除此之外,研究还发现,在载流子迁移率足够高的前提下,厚度达数百纳米的光电探测器可以同时满足具有高的响应度和更低的暗电流密度,从而获得更高的比探测率,本章也详细分析了其物理机制。对于某些材料体系,由于阴极界面与活性层的浸润性问题,会限制倒置器件结构的应用。在这种条件下,为了获得高性能的聚合物光电探测器,论文的第四章研究了以聚乙烯基咔唑(PVK)作为阳极界面层、基于PDPP3T:PC_(71)BM混合物薄膜为光活性层的聚合物光电探测器。实验结果表明,与基于以PEDOT:PSS为阳极界面层的器件相比,基于聚乙烯基咔唑(PVK)作为阳极界面层的光电探测器具有更小的暗电流密度,且具有相当的光响应度,从而利于获得更高的比探测率。对于探测器的其他性能参数,比如频率响应、时间响应、线性动态区域等参数,PVK阳极界面取代PEDOT:PSS后它们没有明显的差异,表明这一方法是简便可行的获得高性能光电探测器的重要手段。
[Abstract]:The polymer Photodetector Based on the photodiode structure is a device to capture optical signals and convert them into electrical signals. Compared with the inorganic photodetectors, polymer photodetectors have many unique advantages, such as light quality, rich material sources and large scale production, which are being paid more and more attention. As a matter of fact, the relationship between polymer photodetectors and organic / polymer solar cells is very close. Both have the same device structure and the photoelectric conversion process is the same. The ratio detection rate is a key performance indicator of the photodetector. At present, more and more than 10~ (12) Jones organic photodetectors are reported. The key performance index of the photoelectric detector can be compared with the inorganic photodetector. In order to further improve the performance of the polymer photodetectors, in addition to the new materials which need more excellent performance, the working mechanism and regulation factors of the photodetectors are further studied. In recent years, the literature reports have shown that as a technical means, Organic solvent vapor annealing (SVA) has been proved to be effective in regulating the micromorphology of the organic / polymer photoactive layer, which is helpful to the separation and charge transport of the exciton, thus inhibiting the carrier recombination and improving the short-circuit current of the device. In the second chapter, in the second chapter, we regulate the morphology of the PCDTBT:PC_ (71) BM mixture film by using the tetrahydrofuran solvent for the solvent vapor annealing treatment of the active layer of the detector, and successfully raised the photoacoustic response of the detector from 90 mA/W to 185 mA/W, increasing by more than 100%, In addition, the dark current density of the detector is avoided, and the ratio detection rate of the detector is increased from 1.86 x 10~ (12) Jones to 5.94 * 10~ (12) Jones. in the third chapter of the paper. We have prepared a polymer Photodetector Based on PBDTTT-C-T:PC_ (71) BM and inverted structure, and compared it with the detector of the positive structure. The experiment shows that two The external quantum efficiency (EQE) of the device structure is equivalent, but the dark current density of the inverted device is 2 to 3 orders of magnitude smaller than that of the positive device, so the ratio detection rate of the inverted device is much better than that of the conventional positive device. On this basis, we have achieved a peak ratio detection rate of 1.58 * 10~ (13) Jones polymer photodetectors. In addition, The switch ratio of the device reaches 10~5, the frequency response reaches 17 MHz, the linear dynamic zone is about 90 dB, and has excellent comprehensive performance. In connection with the energy level theory of semiconductor / metal contact, the mechanism of the device is analyzed. It is considered that the anode interface MoO_3/Al in the inverted structure has a larger Schottky potential between the polymer semiconductor and the polymer semiconductor. The barrier is the key reason for the suppression of the dark current density. In addition, the study also found that, on the premise of high carrier mobility, the thickness of the photodetectors with a thickness of hundreds of nanometers can meet the high response degree and lower dark current density at the same time, thus obtaining a higher ratio detection rate. This chapter also analyzes its physical mechanism in detail. In some material systems, the application of the inverted device structure will be limited due to the wettability of the cathode and active layers. In this condition, in order to obtain high performance polymer photodetectors, the fourth chapter of the paper studies the use of polyvinyl carbazole (PVK) as an anode interface layer, based on the PDPP3T:PC_ (71) BM mixture film as light. The experimental results show that the photodetectors based on the polyethylene carbazole (PVK) as the anode interface layer have smaller dark current density and have a considerable light response degree compared with the devices based on the anode interface layer based on PEDOT:PSS. For the detector, the detector has a higher detection rate. The performance parameters such as frequency response, time response, linear dynamic region and other parameters, and there is no obvious difference between the PVK anode interface instead of PEDOT:PSS, indicating that this method is an important means to obtain high performance photodetectors.

【学位授予单位】：华南理工大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN15

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