• Acta Photonica Sinica
  • Vol. 52, Issue 6, 0604002 (2023)
Ruliang ZHANG, Mingchao PI, Tao AN*, Gang LU, and Qian WANG
Author Affiliations
  • College of Automation and Information Engineering, Xi'an University of Technology, Xi'an 710048, China
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    DOI: 10.3788/gzxb20235206.0604002 Cite this Article
    Ruliang ZHANG, Mingchao PI, Tao AN, Gang LU, Qian WANG. Characteristics of Ternary Organic Photodetectors Based on P3HT∶PC61BM∶ITIC Dual Acceptors[J]. Acta Photonica Sinica, 2023, 52(6): 0604002 Copy Citation Text show less

    Abstract

    Traditional Organ Photodetectors (OPDs) respond not enough in long-wave region, and it is difficult to support panchromatic detection from ultraviolet to infrared regions. In order to overcome the weak absorption ability, researchers adopted a ternary heterojunction structure and the material of complementary absorption spectra. Ternary polymer high-performance OPDs, with ultra-broad spectral response, in panchromatic range, have been reported by mixing the third component. However, there are still problems existing, such as low detection rate, insufficient photoelectric characteristics, and low spectral response uniformity, which are the current research focuses in OPDs.In order to realize panchromatic response to three primary colors, a ternary active layer with heterojunction structure was introduced to broaden spectra by mixing non-fullerene receptor ITIC in P3HT∶PCBM, which can improve detection performance by achieving mobility balance and surface morphology of active layer. In the proposed ternary active layer, polymer P3HT was used as the donor, while fullerene PC61BM and non-fullerene ITIC were adopted as acceptors. The influence of ITIC acceptor mass ratio on photoelectric performance of the detector was mainly studied.The optical characteristic analysis of proposed ternary OPDs indicates that the main material P3HT∶PC61BM film has good light absorption ability from 400 to 600 nm. Moreover, ITIC molecules have stronger absorption abilty in red light region, and main absorption peak is located at 702 nm. Ternary blend film produces a new absorption peak in the range of 600 nm to 750 nm. With gradual increase of ITIC ratio, the absorption ability of blend film in long-wave region enhances. By changing the ratio of PC61BM and ITIC, the absorption intensity of long-wave region can be effectively adjusted.In electrical characteristic, the J-V tests show that dark current density gradually reduces as dual acceptors increase Under red light, the bright current density increases first and then decreases with increasing of the mass ratio of ITIC. As the mass ratio of the active layer was 10∶8∶2, the red current density reached a maximum of 1.91×10-4 A·cm-2. Mixing ITIC into an active layer enhances photocurrent absorption in red light and carriers transport.ITIC influence on the electrical characteristics in the full spectrum was analyzed with External Quantum Efficiency (EQE) spectroscopy at different mass ratios. The EQE of ternary OPDs with ITIC extends to 800 nm, which is attributed to mixing ITIC to promote absorption in long-wave band. The effect on the charge dynamics process in active layer was investigated by fluorescence quenching experiment, to analyze charge transfer inside different mass ratios blend. Photoluminescence spectroscopy (PL) intensity of P3HT is greatly quenched in blended film, which indicates charge transfer existing between P3HT and ITIC. It improves the internal exciton dissociation efficiency and significantly increases photocurrent. By interaction experiments between dual acceptors PC61BM and ITIC, the photocurrent density of mixture is larger than that of single. Charge transfer can improve photocurrent introduction, which enhances light absorption ability and forms more efficient exciton dissociation surfaces.In summary, an appropriate ratio of non-fullerene ITIC mixed into P3HT:PC61BM bulk heterojunction structure can widen OPDs spectrum to 400~800 nm. As a mass ratio of P3HT:PC61BM:ITIC is 10∶8∶2, the EQE of ternary OPDs in three primary colors is up to 56%, 68% and 52%, respectively, and specific detection rate (D*) of three components are up to 1012 Jones in the range of 400~700 nm. Response spectra range is broadened from 600 nm to 800 nm. ITIC compensates absorption of binary blend film in long-wave range, achieves high and balanced carrier mobility ability. ITIC dissociates with original donor and acceptor, which improves light current. Moreover, ITIC also reduces dark current by promoting thin film crystallization and weakening bimolecular recombination.In conclusion, the proposed dual acceptors ternary organic photodetector with complementary absorption ranges, has high mobility of fullerene in active layer film and strong absorption non-fullerene in red and near-infrared light, which contributes to wide spectrum and high sensitivity OPDs.
    Ruliang ZHANG, Mingchao PI, Tao AN, Gang LU, Qian WANG. Characteristics of Ternary Organic Photodetectors Based on P3HT∶PC61BM∶ITIC Dual Acceptors[J]. Acta Photonica Sinica, 2023, 52(6): 0604002
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