【作者】 曹洋；

【导师】 Vincenzo Pecunia；

【作者基本信息】 苏州大学 ， 化学， 2020， 硕士

【摘要】 有机半导体在光电探测上因为有着良好的柔性、可溶液法加工、低成本、化学多功能性等各种优点受到了广泛的关注。近些年来,随着合成技术的进步,越来越多的非富勒烯受体材料出现在人们的视野里。它们的出现克服了富勒烯遇到的诸如光吸收弱、薄膜形态不稳定等挑战,极大地吸引了研究者们的兴趣。传统的光电探测器成像技术往往需要借助于滤光片来进行颜色识别,该法有着空间分辨率受限、结构复杂、成本较高等缺点。在这里,我们采用有机半导体窄带吸收的策略制备出窄光谱有机光电探测器解决了上述问题。所谓的窄带吸收是依赖于仅在特定光谱范围内有吸收的光敏层,而窄带型光电探测器在颜色识别时是无滤光片的,并且可以通过堆叠结构的方式实现多色探测,这也为彩色成像的应用开辟了道路。鉴于上述非富勒烯受体和窄光谱探测的潜在吸引力,我们选择了一种在绿光区有窄带吸收的非富勒烯受体材料Pho-BSubPc,分别与三种给体材料混合,通过溶液法制备出最高外量子产率为39.60%,响应半高峰宽为130 nm的窄带绿光有机光电探测器。该效率在目前的溶液法制备的窄带响应型绿光有机光电探测器中是最高的。具体工作如下:首先我们探索了基于DBQA:Pho-BSubPc型的器件。DBQA是一种可溶的喹吖啶酮衍生物,它在绿光区有着较窄的吸收且与Pho-BSubPc吸收谱有部分重叠。通过溶液混合制得的共混膜在绿光区显现出较窄的吸收,在1:1配比下,其吸收半高峰宽为89 nm。基于该比例制备的器件在绿光区域有较窄的光谱响应,其半高峰宽为140 nm,EQE最大值为3.23%。考虑到DBQA较长的侧链可能对体异质结中给受体的结合有影响,我们又选择了一种在分子结构上与DBQA不同的给体材料QA,QA分子是没有侧链的。由此我们可以来探究不同结构喹吖啶酮材料的选择对器件薄膜形貌和光电转化效率的影响。在1:1配比下,其吸收半高峰宽为86 nm。基于该比例制备的器件在绿光区域中得到了较高的EQE和比探测率,分别为39.60%和1.31 × 1013 Jones,其EQE半高峰宽为130 nm。最后,为了进一步探索基于该法制备的器件是否有更窄响应谱带的可能性,我们选择了 一种在可见光区几乎没有吸收的聚合物给体材料PTAA和Pho-BSubPc混合制备成器件。在1:1配比下,其吸收半高峰宽为76nm。基于该比例制备的器件在绿光区域中得到的EQE最大值为8.15%,半高峰宽为116 nm。综上所述,本论文基于非富勒烯受体材料Pho-BSubPc,通过不同给体材料的筛选,最终制备出高效率的绿光窄光谱响应器件。揭示了溶液法制备的基于非富勒烯受体材料Pho-BSubPc的光电探测器在绿光区域内高效探测的潜力,为彩色成像应用提供了理论基础和技术支撑。更多还原

【Abstract】 Organic semiconductors have attracted extensive attention for photodetection due to their manifold advantages,including good flexibility,solution processability,low cost,chemical versatility,etc.Recent synthetic progress has led to the development of non-fullerene acceptors which overcome some of the challenges encountered with fullerenes,such as weak light absorption and unstable film morphology,attracting great research interest.Traditional photodetector imaging technology often requires color discrimination with filters.This method has the disadvantages of limited spatial resolution,complicated structure,high cost,etc.Herein,we use the narrowband-absorption strategy of organic semiconductors to fabricate narrowband organic photodetectors to solve the above problems.Narrowband photodetection with organic semiconductors usually involves the narrowband-absorption approach.This relies on a photoactive layer exclusively absorbing in a specific spectral range,leading to a strong light response in the same range.Narrowband-absorption-type photodetectors are inherently non-filtered.Additionally,they can potentially deliver multicolor detection in a stacked configuration without having to resort to a colour filter array,thus potentially enabling superior imaging performance.Considering the attractiveness of non-fullerene acceptors and narrowband-absorption-type photodetection,herein we study several solution-based routes to green-sensitive light detection based on narrowband-absorption-type devices comprising a non-fullerene acceptor.The non-fullerene acceptor of choice is Pho-BSubPc,which has a narrow absorbance in the green region.We evaluate the performance of this acceptor in blends with three different donor materials,fabricating devices via a facile solution-based route.Concrete work list as below:We firstly explore photodetectors in which Pho-BSubPc is blended with a soluble quinacridone derivative donor,DBQA,which has a narrow absorption in the green region that overlaps well with that of Pho-BSubPc.DBQA:Pho-BSubPc films manifest a narrow absorption in the green region,with a FWHM of 89 nm at 1:1 ratio.Devices based on such a blend result in a narrow EQE spectrum in the green region,with a FWHM of 140 nm and a maximum value of 3.23%.Considering that the side chain of DBQA may have a negative impact on the intermixing of the donor and acceptor in a bulk heterojunction,we then consider another quinacridone donor named QA which differs from DBQA in molecular structure.The QA molecule is without side chain.We are thus able to compare how the different choice of quinacridone impacts film morphology and photoconversion process.The absorbance FWHM of blend film is 89 nm.We find that QA:Pho-BSubPc devices obtain the highest EQE of 39.60%with a FWHM of 130 nm and the highest specific detectivity of 4.02 × 1011 Jones at 1:1 ratio.Finally,in order to explore the possibility of fabricating solution-based photodetectors with a narrower FWHMEQE,we combine Pho-BSubPc with a polymer donor named PTAA,which has a very weak absorption through the visible range.We get a FWHM of 76 nm of blend film absorbance.In devices based on a 1:1 ratio,the highest EQE is of 8.15%with a FWHM of 116 nm in the green region.In conclusion,we finally fabricated a high-efficiency green light narrowband response device on the non-fullerene acceptor material Pho-BSubPc,through the screening of different donor materials.This thesis reveals that solution-processed photoactive layers based on Pho-BSubPc as a non-fullerene acceptor deliver good potential in narrowband green light detection,as relevant to applications in color imaging.更多还原