具有光电倍增的宽光谱三相体异质结有机彩色探测器  

Organic color photodetectors based on tri-phase bulk heterojunction with wide sectrum and photoelectronic mltiplication

作　　者：安涛[1] 涂传宝 龚伟 An Tao;Tu Chuan-Bao;Gong Wei(Department of Electronic Engineering,Xi＇an University of Technology,Xi＇an 710048,China)

机构地区：[1]西安理工大学电子工程系,西安710048

出　　处：《物理学报》2018年第19期329-337,共9页Acta Physica Sinica

基　　金：陕西省自然科学基金(批准号:2015JM6267)资助的课题~~

摘　　要：实验研究了P3HT:PBDT-TT-F:PCBM三相体异质结活性层光谱拓宽及其材料混合度对探测器光电特性的影响以及陷阱辅助光电倍增的机理.在此基础上,获得了一个覆盖350—750 nm波长范围的彩色探测器.该探测器在-1 V低偏压下红绿蓝三基色的光响应度和外量子效率分别达到了470, 381, 450 mA/W和93%,89%, 121%,比探测率均接近10^(12)Jones,且各基色的特性参数最大平均相对偏差均小于20%,同时频率带宽分别达到了5, 8, 8 kHz.结果表明:在保持二相体异质结薄膜原有微观形貌下,掺入少量光谱拓宽材料可实现活性层吸收光谱的拓宽.利用能级陷阱中电子的辅助作用引入外电路空穴注入,可实现探测器光电倍增.通过调节三相材料的混合度可实现基色间探测能力的均衡性.In order to obtain highly sensitive broadband organic photodetectors（OPDs） used for image sensors with the stable ability to detect three primary colors（RGB）, in this paper, the spectral broadening of organic active layer based on tri-phase bulk heterojunction formed by P3 HT：PCBM doped with narrow band material PBDT-TT-F which absorbs red light is investigated. The influences of PBDT-TT-F doping ratio on the morphology of active layer film and detector photoelectric properties are further analyzed. Finally, the operating mechanism of trap-assisted photoelectronic multiplication is discussed. On this basis, the detector with 350–750 nm wide spectrum is obtained where the optimum mixing ratio of P3HT：PCBM：PBDT-TT-F is 12 ： 8 ： 3. At a small reverse bias of 1 V, the values of responsivity and external quantum efficiency of the photodetector can reach 470, 381, 450 mA/W and 93%, 89%, 121% respectively under the illumination of three primary colors and its normalized detectivity to the RGB is close to 10^（12） Jones. Additionally,the maximum relative difference between each parameter and its average value is lower than 20%; the bandwidths are 5, 8, and 8 kHz respectively, which reach the imaging requirements for image sensors. The experimental results show that not only the absorption spectra of the active layer can be broadened but also the carriers collection efficiency of respective electrodes can be well maintained by adding a small quantity of spectral broadening material while keeping the microstructure of the original binary bulk heterojunction. Utilizing the reasonable combination of materials to form electron traps, photoelectronic multiplication can be realized by trap-assisted hole tunneling injection from the Al cathode into active layer, and thus improving the normalized detectivity. Moreover, in order to detect different light intensities,the hole injection barrier width should be controlled by the corresponding light intensity. The resulting OPD shows a good liner response to all

关 键 词：有机彩色图像传感器 光电探测器 三相体异质结 光电倍增 

分 类 号：TH74[机械工程—光学工程]