Limits...
Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors.

Lei Y, Deng P, Li J, Lin M, Zhu F, Ng TW, Lee CS, Ong BS - Sci Rep (2016)

Bottom Line: Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics.Conversely, the readily soluble, low-MW D-A polymers give low mobility.With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm(2)V(-1)s(-1)), on/off ratio (10(7)), and other desirable field-effect properties that meet impactful OFET application requirements.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Institute of Advanced Materials, Hong Kong Baptist University, Hong Kong SAR, P. R. China.

ABSTRACT
Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility. Conversely, the readily soluble, low-MW D-A polymers give low mobility. We report herein a facile solution process which transformed a lower-MW, low-mobility diketopyrrolopyrrole-dithienylthieno[3,2-b]thiophene (I) into a high crystalline order and high-mobility semiconductor for OFETs applications. The process involved solution fabrication of a channel semiconductor film from a lower-MW (I) and polystyrene blends. With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm(2)V(-1)s(-1)), on/off ratio (10(7)), and other desirable field-effect properties that meet impactful OFET application requirements.

No MeSH data available.


Related in: MedlinePlus

Field-effect transistor properties of OFETs with (I) and (I)/polystyrene semiconductor films.(a) Bottom gate-top contact experimental transistor structure; (b) typical transfer characteristics and (c) output curves of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors; (d) mobility distributions of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4835732&req=5

f5: Field-effect transistor properties of OFETs with (I) and (I)/polystyrene semiconductor films.(a) Bottom gate-top contact experimental transistor structure; (b) typical transfer characteristics and (c) output curves of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors; (d) mobility distributions of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors.

Mentions: The electrical performance characteristics of the (I)/polystyrene films as channel semiconductors in OFETs were investigated using a bottom gate-top contact transistor configuration (Fig. 5a). The transfer and output curves of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductor films are shown in Fig. 5b,c, and the extracted field-effect mobility in the saturated regime, on/off ratio, threshold voltages summarized in Table 1. For completeness, typical transfer and output curves of OFETs with (I)/polystyrene films of various polystyrene loadings as channel layers are also given in Figure S2 (Supplementary Information). As noted, the mobility and on/off ratio increased with polystyrene loading in the (I)/polystyrene film up to about 60 wt%, where a mobility as high as 8.25 cm2 V−1s−1 and on/off ratio of ~107 were attained. These results represented more than a factor of five higher in mobility and two orders of magnitude better in on/off ratio than similar devices with neat (I) as channel semiconductor (mobility ~1.5 cm2 V−1s−1 and on/off ratio ~105). Furthermore, the average mobility (average ~6.76 cm2 V−1s−1) was comparable to those of high-MW (~500 kg mol−1) materials even though the π-π stacking distance was somewhat larger10. The substantially higher mobility correlate very well with the beneficial, predominantly single α-polymorph phase and interpenetrating nanowire network of (I) in polystyrene matrix, which served as a long-range percolated pathway for efficient charge transport between source/drain electrodes. The extremely high on/off ratio was attributable to the insulating nature of the polystyrene matrix which helped suppress leakage current (Fig. 5b). We also noted that the threshold voltage (Vth) shift decreased with increased polystyrene loading in the (I)/polystyrene film (Table 1), and smallest positive threshold shift of 1.7 V was observed at 60 wt% polystyrene loading. In addition, the (I)/polystyrene devices exhibited smaller hysteresis effect than those with neat (I) semiconductor (Fig. S2a–e), again with the 60 wt% polystyrene devices displaying the smallest hysteresis effect. These results further demonstrate the definitive role of polystyrene in helping eliminate charge trapping at the polymer/SiO2 interface by passivating the surface of OTS-18-modified SiO2 dielectric. Beyond 60 wt% polystyrene loadings, degradation in charge transport properties was observed. This was largely due to the dilution effect, disrupting the interconnectivity of the nanowire network as could be seen in the (I)/polystyrene (20/80 wt%) film where the nanowire network appeared to be significantly degraded (Fig. 2e). The observed mobility was much lower at 3.34 cm2 V−1s−1 while maintaining the same high on/off ratio of ~107 and relative small positive threshold shift of 4.6 V owing to the insulating effect of polystyrene.


Solution-Processed Donor-Acceptor Polymer Nanowire Network Semiconductors For High-Performance Field-Effect Transistors.

Lei Y, Deng P, Li J, Lin M, Zhu F, Ng TW, Lee CS, Ong BS - Sci Rep (2016)

Field-effect transistor properties of OFETs with (I) and (I)/polystyrene semiconductor films.(a) Bottom gate-top contact experimental transistor structure; (b) typical transfer characteristics and (c) output curves of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors; (d) mobility distributions of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4835732&req=5

f5: Field-effect transistor properties of OFETs with (I) and (I)/polystyrene semiconductor films.(a) Bottom gate-top contact experimental transistor structure; (b) typical transfer characteristics and (c) output curves of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors; (d) mobility distributions of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductors.
Mentions: The electrical performance characteristics of the (I)/polystyrene films as channel semiconductors in OFETs were investigated using a bottom gate-top contact transistor configuration (Fig. 5a). The transfer and output curves of OFETs with (I) and (I)/polystyrene (40/60 wt%) channel semiconductor films are shown in Fig. 5b,c, and the extracted field-effect mobility in the saturated regime, on/off ratio, threshold voltages summarized in Table 1. For completeness, typical transfer and output curves of OFETs with (I)/polystyrene films of various polystyrene loadings as channel layers are also given in Figure S2 (Supplementary Information). As noted, the mobility and on/off ratio increased with polystyrene loading in the (I)/polystyrene film up to about 60 wt%, where a mobility as high as 8.25 cm2 V−1s−1 and on/off ratio of ~107 were attained. These results represented more than a factor of five higher in mobility and two orders of magnitude better in on/off ratio than similar devices with neat (I) as channel semiconductor (mobility ~1.5 cm2 V−1s−1 and on/off ratio ~105). Furthermore, the average mobility (average ~6.76 cm2 V−1s−1) was comparable to those of high-MW (~500 kg mol−1) materials even though the π-π stacking distance was somewhat larger10. The substantially higher mobility correlate very well with the beneficial, predominantly single α-polymorph phase and interpenetrating nanowire network of (I) in polystyrene matrix, which served as a long-range percolated pathway for efficient charge transport between source/drain electrodes. The extremely high on/off ratio was attributable to the insulating nature of the polystyrene matrix which helped suppress leakage current (Fig. 5b). We also noted that the threshold voltage (Vth) shift decreased with increased polystyrene loading in the (I)/polystyrene film (Table 1), and smallest positive threshold shift of 1.7 V was observed at 60 wt% polystyrene loading. In addition, the (I)/polystyrene devices exhibited smaller hysteresis effect than those with neat (I) semiconductor (Fig. S2a–e), again with the 60 wt% polystyrene devices displaying the smallest hysteresis effect. These results further demonstrate the definitive role of polystyrene in helping eliminate charge trapping at the polymer/SiO2 interface by passivating the surface of OTS-18-modified SiO2 dielectric. Beyond 60 wt% polystyrene loadings, degradation in charge transport properties was observed. This was largely due to the dilution effect, disrupting the interconnectivity of the nanowire network as could be seen in the (I)/polystyrene (20/80 wt%) film where the nanowire network appeared to be significantly degraded (Fig. 2e). The observed mobility was much lower at 3.34 cm2 V−1s−1 while maintaining the same high on/off ratio of ~107 and relative small positive threshold shift of 4.6 V owing to the insulating effect of polystyrene.

Bottom Line: Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics.Conversely, the readily soluble, low-MW D-A polymers give low mobility.With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm(2)V(-1)s(-1)), on/off ratio (10(7)), and other desirable field-effect properties that meet impactful OFET application requirements.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Institute of Advanced Materials, Hong Kong Baptist University, Hong Kong SAR, P. R. China.

ABSTRACT
Organic field-effect transistors (OFETs) represent a low-cost transistor technology for creating next-generation large-area, flexible and ultra-low-cost electronics. Conjugated electron donor-acceptor (D-A) polymers have surfaced as ideal channel semiconductor candidates for OFETs. However, high-molecular weight (MW) D-A polymer semiconductors, which offer high field-effect mobility, generally suffer from processing complications due to limited solubility. Conversely, the readily soluble, low-MW D-A polymers give low mobility. We report herein a facile solution process which transformed a lower-MW, low-mobility diketopyrrolopyrrole-dithienylthieno[3,2-b]thiophene (I) into a high crystalline order and high-mobility semiconductor for OFETs applications. The process involved solution fabrication of a channel semiconductor film from a lower-MW (I) and polystyrene blends. With the help of cooperative shifting motion of polystyrene chain segments, (I) readily self-assembled and crystallized out in the polystyrene matrix as an interpenetrating, nanowire semiconductor network, providing significantly enhanced mobility (over 8 cm(2)V(-1)s(-1)), on/off ratio (10(7)), and other desirable field-effect properties that meet impactful OFET application requirements.

No MeSH data available.


Related in: MedlinePlus