摘要
Photomultiplication(PM) structure has been widely employed to improve the optoelectronic performance of organic photodetectors(OPDs). However, most PM-type OPDs require a high negative operating voltage or complex fabrication. For obtaining high-efficiency OPDs with low voltage and easy process, here the bulk heterojunction(BHJ) structure of high exciton dissociation efficiency combined with the method of trap-assisted PM are applied to the OPDs.In this paper, we investigate the operating mechanism of OPDs based on poly(3-hexylthiophene)(P3 HT):(phenyl-C61-butyric-acid-methyl-ester)(PC61 BM), and poly-{[4,8-bis[(2-ethylhexyl)oxy]-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[3-fluore-2-(octyloxy)carbonyl-thieno[3,4-b]thiophene-4,6-diyl]}(PBDT-TT-F):PC_(61)BM doped with C_(60) as active layer.Furthermore, the influence of C_(60) concentration on the optoelectronic performances is also discussed. With 1.6 wt.% C_(60)added, the P3 HT:PC_(61)BM:C_(60) OPD exhibits a 327.5% external quantum efficiency, a 1.21 A·W^(-1) responsivity, and a4.22 x 1012 Jones normalized detectivity at-1 V under 460 nm(0.21 mW·cm^(-2)) illumination. The experimental results show that the effective electron traps can be formed by doping a small weight of C_(60) into BHJ active layer. Thus the PM-type OPDs can be realized, which benefits from the cathode hole tunneling injection assisted by the trapped electrons in C_(60) near the A1 side. The efficiency of PM is related to the C_(60) concentration. The present study provides theoretical basis and method for the design of highly sensitive OPDs with low operating voltage and facile fabrication.
Photomultiplication(PM) structure has been widely employed to improve the optoelectronic performance of organic photodetectors(OPDs). However, most PM-type OPDs require a high negative operating voltage or complex fabrication. For obtaining high-efficiency OPDs with low voltage and easy process, here the bulk heterojunction(BHJ) structure of high exciton dissociation efficiency combined with the method of trap-assisted PM are applied to the OPDs.In this paper, we investigate the operating mechanism of OPDs based on poly(3-hexylthiophene)(P3 HT):(phenyl-C61-butyric-acid-methyl-ester)(PC61 BM), and poly-{[4,8-bis[(2-ethylhexyl)oxy]-benzo[1,2-b:4,5-b]dithiophene-2,6-diyl]-alt-[3-fluore-2-(octyloxy)carbonyl-thieno[3,4-b]thiophene-4,6-diyl]}(PBDT-TT-F):PC_(61)BM doped with C_(60) as active layer.Furthermore, the influence of C_(60) concentration on the optoelectronic performances is also discussed. With 1.6 wt.% C_(60)added, the P3 HT:PC_(61)BM:C_(60) OPD exhibits a 327.5% external quantum efficiency, a 1.21 A·W^(-1) responsivity, and a4.22 x 1012 Jones normalized detectivity at-1 V under 460 nm(0.21 mW·cm^(-2)) illumination. The experimental results show that the effective electron traps can be formed by doping a small weight of C_(60) into BHJ active layer. Thus the PM-type OPDs can be realized, which benefits from the cathode hole tunneling injection assisted by the trapped electrons in C_(60) near the A1 side. The efficiency of PM is related to the C_(60) concentration. The present study provides theoretical basis and method for the design of highly sensitive OPDs with low operating voltage and facile fabrication.
基金
supported by the National Natural Science Foundation of China(Grant No.61106043)
the Natural Science Foundation of Shaanxi Province,China(Grant No.2015JM6267)
Program of Xi’an University of Technology,China(Grant No.103-4515013)
