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Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics.

Bucella SG, Luzio A, Gann E, Thomsen L, McNeill CR, Pace G, Perinot A, Chen Z, Facchetti A, Caironi M - Nat Commun (2015)

Bottom Line: As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics.Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm(2) V(-1) s(-1), allowing very simple device architectures to operate at 3.3 MHz.Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

View Article: PubMed Central - PubMed

Affiliation: Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, Via Pascoli 70/3, Milano 20133, Italy.

ABSTRACT
High-mobility semiconducting polymers offer the opportunity to develop flexible and large-area electronics for several applications, including wearable, portable and distributed sensors, monitoring and actuating devices. An enabler of this technology is a scalable printing process achieving uniform electrical performances over large area. As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics. By combining pre-aggregating solvents for formulating the semiconductor and by adopting a room temperature wired bar-coating technique, here we demonstrate the fast deposition of submonolayers and nanostructured films of a model electron-transporting polymer. Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm(2) V(-1) s(-1), allowing very simple device architectures to operate at 3.3 MHz. Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

No MeSH data available.


Effect of coating speed and of molecular weight.(a) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating at different velocity (1, 3 and 6 m min−1) a solution of P(NDI2OD-T2) with Mn of 26.6 KDa and PDI of 3.2, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. The solution concentration is 5 g l−1 in mesitylene. (b) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating solutions of P(NDI2OD-T2) with different Mn and PDI, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. Solution concentration (5 g l−1 in mesitylene) and coating speed (3 m min−1) were kept constant.
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f4: Effect of coating speed and of molecular weight.(a) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating at different velocity (1, 3 and 6 m min−1) a solution of P(NDI2OD-T2) with Mn of 26.6 KDa and PDI of 3.2, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. The solution concentration is 5 g l−1 in mesitylene. (b) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating solutions of P(NDI2OD-T2) with different Mn and PDI, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. Solution concentration (5 g l−1 in mesitylene) and coating speed (3 m min−1) were kept constant.

Mentions: To test the effect of the coating speed on the electrical properties of bar-coated thin films, we perform coating at different speeds, including 1, 3 and 6 m min−1. The corresponding FETs data are reported in Fig. 4a. In all cases it is possible to achieve alignment and to observe transport anisotropy. In the case of the slower speed of 1 m min−1, the anisotropy is the weakest (μsat-para/μsat-perp=6.4) and the average saturation mobility in the parallel case is only μsat-para=1.41 cm2 V−1 s−1, indicating that the alignment is not as efficient as at 3 m min−1, likely owing to a reduced shear. A faster coating speed of 6 m min−1 produces an anisotropy which is only slightly inferior to the 3 m min−1 case (μsat-para/μsat-perp=20.1), and where the average saturation mobility in the parallel case reaches μsat-para=3.62 cm2 V−1 s−1. To test also the effect of molecular weight, we perform coating tests with a series of batches with the following average molecular weight, Mn (and polidispersity, PDI): 5 kDa (1.8), 20.8 kDa (2.4), 26.6 (3.2), 44.8 kDa (2.6) (in Fig. 4 referred as P1, P2, P3 and P4, respectively), while keeping constant the solution concentration (5 mg ml−1 in mesitylene) and the coating speed (3 m min−1). The results, in terms of saturation mobility for devices probing the transport parallel and perpendicularly to the coating direction, are reported in Fig. 4b. These results show that a very low Mn of 5 kDa does not allow observing any anisotropy, as an effect of the impossibility to align the polymer backbones. This is likely due to an ineffective aggregation in mesitylene solution, as evidenced by ultraviolet–vis spectra (Supplementary Fig. 8). This results also in a poor average mobility of 0.23 cm2 V−1 s−1. The alignment, and consequent anisotropy, is very effective with Mn=20.8 kDa (PDI=2.4) and Mn=26.6 kDa (PDI=3.2). Between the two, the 26.6 kDa batch shows the best results. However, since the Mn are very close, we cannot exclude an effect of the different PDI of the two batches. When we adopt consistently higher Mn, as in the case of the 44.8 kDa batch, we enter again a regime where alignment is problematic, likely owing to a too strong entanglement of the chains. In this case we do observe a small anisotropy, but the average mobility in the parallel case is limited to 0.29 cm2 V−1 s−1.


Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics.

Bucella SG, Luzio A, Gann E, Thomsen L, McNeill CR, Pace G, Perinot A, Chen Z, Facchetti A, Caironi M - Nat Commun (2015)

Effect of coating speed and of molecular weight.(a) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating at different velocity (1, 3 and 6 m min−1) a solution of P(NDI2OD-T2) with Mn of 26.6 KDa and PDI of 3.2, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. The solution concentration is 5 g l−1 in mesitylene. (b) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating solutions of P(NDI2OD-T2) with different Mn and PDI, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. Solution concentration (5 g l−1 in mesitylene) and coating speed (3 m min−1) were kept constant.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4596007&req=5

f4: Effect of coating speed and of molecular weight.(a) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating at different velocity (1, 3 and 6 m min−1) a solution of P(NDI2OD-T2) with Mn of 26.6 KDa and PDI of 3.2, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. The solution concentration is 5 g l−1 in mesitylene. (b) Saturation mobility (VGS=VDS=60 V) for FETs fabricated by bar-coating solutions of P(NDI2OD-T2) with different Mn and PDI, probing the transport parallel (black dots) and perpendicularly (red dots) to the coating direction. Solution concentration (5 g l−1 in mesitylene) and coating speed (3 m min−1) were kept constant.
Mentions: To test the effect of the coating speed on the electrical properties of bar-coated thin films, we perform coating at different speeds, including 1, 3 and 6 m min−1. The corresponding FETs data are reported in Fig. 4a. In all cases it is possible to achieve alignment and to observe transport anisotropy. In the case of the slower speed of 1 m min−1, the anisotropy is the weakest (μsat-para/μsat-perp=6.4) and the average saturation mobility in the parallel case is only μsat-para=1.41 cm2 V−1 s−1, indicating that the alignment is not as efficient as at 3 m min−1, likely owing to a reduced shear. A faster coating speed of 6 m min−1 produces an anisotropy which is only slightly inferior to the 3 m min−1 case (μsat-para/μsat-perp=20.1), and where the average saturation mobility in the parallel case reaches μsat-para=3.62 cm2 V−1 s−1. To test also the effect of molecular weight, we perform coating tests with a series of batches with the following average molecular weight, Mn (and polidispersity, PDI): 5 kDa (1.8), 20.8 kDa (2.4), 26.6 (3.2), 44.8 kDa (2.6) (in Fig. 4 referred as P1, P2, P3 and P4, respectively), while keeping constant the solution concentration (5 mg ml−1 in mesitylene) and the coating speed (3 m min−1). The results, in terms of saturation mobility for devices probing the transport parallel and perpendicularly to the coating direction, are reported in Fig. 4b. These results show that a very low Mn of 5 kDa does not allow observing any anisotropy, as an effect of the impossibility to align the polymer backbones. This is likely due to an ineffective aggregation in mesitylene solution, as evidenced by ultraviolet–vis spectra (Supplementary Fig. 8). This results also in a poor average mobility of 0.23 cm2 V−1 s−1. The alignment, and consequent anisotropy, is very effective with Mn=20.8 kDa (PDI=2.4) and Mn=26.6 kDa (PDI=3.2). Between the two, the 26.6 kDa batch shows the best results. However, since the Mn are very close, we cannot exclude an effect of the different PDI of the two batches. When we adopt consistently higher Mn, as in the case of the 44.8 kDa batch, we enter again a regime where alignment is problematic, likely owing to a too strong entanglement of the chains. In this case we do observe a small anisotropy, but the average mobility in the parallel case is limited to 0.29 cm2 V−1 s−1.

Bottom Line: As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics.Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm(2) V(-1) s(-1), allowing very simple device architectures to operate at 3.3 MHz.Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

View Article: PubMed Central - PubMed

Affiliation: Center for Nano Science and Technology @PoliMi, Istituto Italiano di Tecnologia, Via Pascoli 70/3, Milano 20133, Italy.

ABSTRACT
High-mobility semiconducting polymers offer the opportunity to develop flexible and large-area electronics for several applications, including wearable, portable and distributed sensors, monitoring and actuating devices. An enabler of this technology is a scalable printing process achieving uniform electrical performances over large area. As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics. By combining pre-aggregating solvents for formulating the semiconductor and by adopting a room temperature wired bar-coating technique, here we demonstrate the fast deposition of submonolayers and nanostructured films of a model electron-transporting polymer. Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm(2) V(-1) s(-1), allowing very simple device architectures to operate at 3.3 MHz. Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

No MeSH data available.