Fobao Huang

A striking performance improvement of fullerene n-channel field-effect transistors via synergistic interfacial modifications

For fullerene based n-channel transistors, remarkably improved device characteristics were achieved via charge injection and transport interfacial synergistic modifications using low-cost aluminium source/drain electrodes. Compared with the reference device without any modifications (device A), the as-fabricated transistor (device H) showed a dramatic improvement of saturation mobility from 0.0026 to 0.3078 cm2 V−1 s−1 with a maximum on–off current ratio of 106 and a minimum subthreshold slope of 1.52 V decade−1. AFM and XRD analysis manifested that the deposited C60 films on PVA/OTS successive-modified SiO2 substrate were highly dense polycrystalline and uniform with larger crystalline grain and less grain boundary. A gap state assisted electron injection mechanism was proposed to explicate the enhanced electrical conductivity considering BCP modification for charge injection interface, which has been well corroborated by a diode-based injection experiment and a theoretical calculation of contact resistances. We further demonstrated the application of the concept modification method to enable comparative time-stable operation of fullerene n-channel transistors. Given many key merits, we believed that this general method using multi-interface modifications could be extended to fabricate other n-channel OFETs with superior electrical performance and stability.

Broadband organic phototransistor with high photoresponse from ultraviolet to near-infrared realized via synergistic effect of trilayer heterostructure

Broadband photodetectors have attracted tremendous attention in recent years because of their extensive industrial and scientific applications for optoelectronic circuits. However, up until now, developing organic phototransistors with a high photoresponse over the broadband spectrum still remains a great challenge due to the lack of broad spectral photosensitive materials. Herein, we report a high-performance broadband phototransistor by adopting an all-organic trilayer heterostructure as an active structure containing three small organic molecules with mutual-complementary photoabsorption spectra. Utilizing the synergistic effect of the high mobility of a fullerene (C60) channel and strong complementary photoabsorption of a C60/3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA)/tin phthalocyanine (SnPc) trilayer heterostructure, a broad high photoresponse from the ultraviolet-visible to the near-infrared region was realized. The photoresponsivity (R), external quantum efficiency (EQE), specific detectivity (D*), and response time reached up to 56.88 A W−1, 15 704%, 9.15 × 1012 Jones, and <0.5 ms at an incident light intensity of 2 μW mm−2, respectively, and the photosensitivity (Pmax) to 6.39 × 105 at a light intensity of 150 μW mm−2, most of which are comparable or even surpass the values achieved by commercial silicon, germanium, and indium gallium arsenide photodetectors, as well as many of inorganic and organic photodetectors reported recently. This synergistic strategy opens up a promising avenue for constructing high-performance all-organic photodetectors with a superior broadband response.