- Nano Express
- Open Access
Effect of In Situ Annealing Treatment on the Mobility and Morphology of TIPS-Pentacene-Based Organic Field-Effect Transistors
© The Author(s). 2017
- Received: 13 June 2017
- Accepted: 16 July 2017
- Published: 23 August 2017
In this work, organic field-effect transistors (OFETs) with a bottom gate top contact structure were fabricated by using a spray-coating method, and the influence of in situ annealing treatment on the OFET performance was investigated. Compared to the conventional post-annealing method, the field-effect mobility of OFET with 60 °C in situ annealing treatment was enhanced nearly four times from 0.056 to 0.191 cm2/Vs. The surface morphologies and the crystallization of TIPS-pentacene films were characterized by optical microscope, atomic force microscope, and X-ray diffraction. We found that the increased mobility was mainly attributed to the improved crystallization and highly ordered TIPS-pentacene molecules.
- Organic field-effect transistors
- In situ annealing treatment
- Field-effect mobility
Organic field-effect transistors (OFETs) have attracted considerable attention as a promising candidate for its practical applications in flexible electronic papers, flat-panel displays, radio frequency identification (RFID) tags, and logic circus [1–7]. Up to now, several strategies such as blade coating [6, 8, 9], ink-jet printing [10, 11], gravure printing [12, 13], and the recently emerged spraying technologies [14–16] have been proved to be efficient methods for the fabrication of electronic devices. Among these methods, spray coating has been investigated intensively due to its unique advantage in manufacturing. Through the spray-coating method, various materials with low solubility in less toxic solvent can be applied due to the requirement of a low solution concentration . Moreover, spray coating makes it possible with higher speed of production and better compatibility to various substrates , and the different shapes of film can be patterned through shadow masks . Additionally, compared to other methods, such as spin casting, blade coating, and gravure printing, the spray-coating process can realize a continuous film without damaging the bottom layer of the device: just simply control the solvent content, droplet size, and solidification dynamics.
In the previous works, some novel manufacturing methods have been applied to achieve high-performance OFETs via spray coating. Khim et al. investigated the effects of the droplet size on the performance of OFETs fabricated using spray-printed organic semiconducting active layers . Park et al. made an intensive study of solvent content by using a solvent-assisted post-treatment method . Meanwhile, substrate heating is demonstrated to be an effective method in enhancing the crystallinity of semiconductor films [21, 22]. For that, multiple research work has been developed. Sarcletti et al. researched the mutual influence of surface energy and substrate temperature on the mobility in organic semiconductors . Also, Padma et al. investigated the influence of substrate temperature on the growth modes of copper phthalocyanine thin films at the dielectric/semiconductor interface . Subsequently, Mikayelyan et al. studied the effect of the substrate temperature on the structure and morphology of the vacuum-evaporated films . And the thermal annealing effect on the crack development also has been investigated . Although a large number of studies have focused on improving the intrinsic electrical properties of device fabrication techniques, the influence of in situ annealing treatment in the research field of spray-coated OFETs has not received much attention. Meanwhile, the conventional solution process of OFETs usually calls for production interruptions and baking treatment as well as the process being time consuming. Therefore, the development of a novel annealing processing technique is thus a key step towards utilizing the full potential of the spray process.
In this study, we introduced a simple in situ annealing treatment in fabricating high-performance OFETs, and various substrate temperatures were applied in the in situ annealing treatment. With the 60 °C in situ annealing treatment, the mobility of the OFET device significantly enhanced from 0.056 to 0.191 cm2/Vs, which was mainly attributed to the improved crystallization and ordered 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) molecules. To elucidate the mechanism of this performance enhancement, optical microscope, atomic force microscope (AFM), and X-ray diffraction (XRD) were used to analyze the morphology and crystallization of the TIPS-pentacene films. Our work demonstrates that with simple in situ annealing treatment, high-performance OFETs with an efficient manufacturing process can be realized by carefully controlling the conditions of the in situ annealing method.
where I DS is the drain-source current, and L (100 μm) and W (1 cm) are the channel length and width, respectively. C i is the capacitance per unit of the dielectric layer, and V GS and V TH are the gate voltage and the threshold voltage, respectively. The surface morphologies of the TIPS-pentacene were characterized with an optical microscope (U-MSSP4, OLYMPUS) and atomic force microscope (AFM) (MFP-3D-BIO, Asylum Research) in a tapping mode, and the structure characterization was taken by X-ray powder diffraction (XRD, TD-3500, Dandong, China) with an accelerating voltage of 30 kV and an applied current of 20 mA.
Electrical characteristics of the OFETs spray coated with post-annealing of 120 °C for 20 min and in situ annealing treatment of 60, 90, and 120 °C, respectively
I on/I off
1.62 × 105
(in situ annealing)
3.47 × 104
(in situ annealing)
3.00 × 102
(in situ annealing)
Not unexpectedly, all devices demonstrated typical p-type transistor characteristics. It can be clearly found that the in situ annealing treatment has tremendous influence on the electronic properties of OFETs. Especially, with the 60 °C in situ annealing treatment, the electrical performance of OFET was successfully enhanced, including a positive shift of V TH (from −1.7 to −0.9 V), and an increasing μ (from 0.056 to 0.191 cm2/Vs); the mobility of device B is almost fourfolds higher than that of the post-annealed device A. However, when applying with 90 °C in situ annealing treatment, an extensive degradation of device performance appears along with the increasing substrate temperature, including a forward drift of V TH from −0.9 to 2.0 V, and a decreasing μ ranged from 0.191 to 0.04 cm2/Vs. Furthermore, when the in situ annealing temperature increased to 120 °C, things get even worse, and an obvious decrease of I on from 12.1 to 0.17 μA and μ from 0.04 to 0.0005 cm2/Vs was obtained. As a result, the performance of devices C and D was much worse than the post-annealed device A.
The representative transfer and output plots of the OFETs prepared by spray-coating method with different annealing treatment are depicted in Fig. 2. It can be clearly seen that device B demonstrates the highest electrical performance, including near zero threshold voltages and a narrow subthreshold swing. However, with the increase of substrate temperature in the in situ annealing treatment, an attenuation of electrical performance was revealed. The subthreshold swing exhibited an obvious trend of increment along with the in situ annealing temperature, which implies a relatively high trap density at the interface between the dielectric and semiconductor layer .
As we can see, the changes in substrate temperature lead to different morphologies and grain size. And the greatest morphology of device B can be ascribed not only to the proper annealing temperature but also to the favored condition for molecular self-organization. When the OFETs are prepared at a relatively low substrate temperature, gentle evaporation of the solvent can be maintained, leading to a reduced solvent evaporation rate, and the consecutive droplets kept the film wet. Actually, this modulation of substrate temperature directly influences the solvent evaporation rate. Lower annealing temperature allows TIPS-pentacene crystals to grow slowly with ordered molecules , while higher substrate temperature contributes to quickly solidification, without a relatively slow drying process of solvent . Thus, a longer time was obtained for molecular self-organization during the spray process, which is responsible for a higher degree of phase separation and a larger domain size [33, 35, 36]. As a consequence, slender and longish grains are formed, and the bridges for carrier transportation in the channel region can be built through these long grains which are longer than 110.8 μm .
In summary, we have fabricated and tested OFETs by spray coating TIPS-pentacene with in situ annealing treatment, and the surface morphologies and the crystallization of the obtained film were investigated. The results show that the electrical performance of TIPS-pentacene-based OFETs has strong correlation with the processing condition of the active layer. With the template temperature of 60 °C, the mobility of OFETs fabricated by in situ annealing method increases from 0.056 to 0.191 cm2/Vs. The performance enhancement was attributed to the higher crystallization and ordered grains. This in situ annealing treatment of the spray-coating method is expected to be an effective way for the fabrication of high-performance OFETs as well as a high potential for low-cost manufacturing and application versatility.
The authors gratefully acknowledge the financial support from the Foundation for Innovation Research Groups of National Natural Science Foundation of China (NSFC) (Grant No. 61421002), the Foundation of NSFC (Grant No. 61675041), and Science & Technology Department of Sichuan Province (Grant Nos. 2016HH0027 and 2016FZ0100).
FY and XW did the most experiments in this work. FY and HF made the research plan, and they contributed to writing the manuscript. YT carried out the data analysis. All the authors read and approved the final manuscript.
Fuqiang Yang received his B.A. degree from Wuhan Textile University in 2015. He has been studying for his Master degree at State Key Laboratory of Electronic Thin Films and Integrated Devices (SKLETFID) and UESTC since 2015, where his main research interests are in OFETs and OFET-based sensors.
Xiaolin Wang has been studying for his B.A. degree at the School of Optoelectronic Information at UESTC since 2016. He has been working as a student at SKLETFID since 2017, where his main research interests are in OFETs and OFET-based sensors.
Huidong Fan received his B.A. degree from the Yingcai Experimental School at UESTC in 2013. He has been studying for his Ph.D. degree at the State Key Laboratory of Electronic Thin Films and Integrated Devices (SKLETFID) at UESTC since 2013, where his main research interests are in OFETs and OFET-based sensors.
Ying Tang got her Ph.D. degree from the Graduate School of Physical Science and Technology at Lanzhou University in 2007. She is a postdoctor of SKLETFID at UESTC majoring in organic electronic materials and devices.
Jianjun Yang got his Ph.D. degree from UESTC in 2002. Now, he is the professor of the State Key Laboratory of Electronic Thin Films and Integrated Devices Zhongshan Branch Office, College of Electronic and Information Engineering, University of Electronic and Technology of China, Zhongshan Institute, majoring in optoelectronic materials and devices.
Junsheng Yu got his Ph.D. degree from the Graduate School of Bio-Applications and System Engineering at Tokyo University of Agriculture and Technology in 2001. He is the Professor of SKLETFID and UESTC majoring in organic photoelectronic and electronic materials and devices.
The authors declare that they have no competing interests.
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- Fujisaki Y, Koga H, Nakajima Y, Nakata M, Tsuji H, Yamamoto T, Kurita T, Nogi M, Shimidzu N (2014) Transparent nanopaper-based flexible organic thin-film transistor array. Adv Funct Mater 24(12):1657–1663View ArticleGoogle Scholar
- Gaspar D, Fernandes SN, De Oliveira AG, Fernandes JG, Grey P, Pontes RV, Martins R, Godinho MH, Fortunato E (2014) Nanocrystalline cellulose applied simultaneously as the gate dielectric and the substrate in flexible field effect transistors. Nanotechnology 25(9):094008View ArticleGoogle Scholar
- Uno M, Kanaoka Y, Cha BS, Isahaya N, Sakai M, Matsui H, Katayama M (2015) Short-channel solution-processed organic semiconductor transistors and their application in high-speed organic complementary circuits and organic rectifiers. Adv Electron Mater 1(12):1500178View ArticleGoogle Scholar
- Yuan Y, Giri G, Ayzner AL, Zoombelt AP, Mannsfeld SC, Chen J, Nordlund D, Toney MF, Huang J, Bao Z (2014) Ultra-high mobility transparent organic thin film transistors grown by an off-centre spin-coating method. Nat Commun 5:3005Google Scholar
- Liang X, Xia J, Dong G, Tian B (2016) Carbon nanotube thin film transistors for flat panel display application. Top Curr Chem 374(6):80View ArticleGoogle Scholar
- Yamamura A, Matsui H, Uno M, Isahaya N, Tanaka Y, Kudo M, Ito M, Mitsui C, Okamoto T, Takeya, J (2017) Painting integrated complementary logic circuits for single-crystal organic transistors: a demonstration of a digital wireless communication sensing tag. Adv Electron Mater. doi:10.1002/aelm.201600456
- Lu G, Pietro RD, Kölln LS, Nasrallah I, Zhou L, Mollinger S, Himmelberger S, Koch N, Salleo A, Neher D (2016) Dual-characteristic transistors based on semiconducting polymer blends. Adv Electron Mater 2(10):1600267View ArticleGoogle Scholar
- Pitsalidis C, Kalfagiannis N, Hastas NA, Karagiannidis PG, Kapnopoulos C, Ioakeimidis A, Logothetidis S (2014) High performance transistors based on the controlled growth of triisopropylsilylethynyl-pentacene crystals via non-isotropic solvent evaporation. RSC Adv 4(40):20804–20813View ArticleGoogle Scholar
- Giri G, Verploegen E, Mannsfeld SC, Atahan S, Kim DH, Lee SY, Becerril HA, Aspuru-Guzik A, Toney MF, Bao Z (2011) Tuning charge transport in solution-sheared organic semiconductors using lattice strain. Nature 480(7378):504–508View ArticleGoogle Scholar
- James DT, Kjellander BC, Smaal WT, Gelinck GH, Combe C, McCulloch I, Wilson R, Burroughes JH, Bradley DDC, Kim JS (2011) Thin-film morphology of inkjet-printed single-droplet organic transistors using polarized raman spectroscopy: effect of blending TIPS-pentacene with insulating polymer. ACS Nano 5(12):9824–9835View ArticleGoogle Scholar
- Cho SY, Ko JM, Jung JY, Lee JY, Choi DH, Lee C (2012) High-performance organic thin film transistors based on inkjet-printed polymer/TIPS pentacene blends. Org Electron 13(8):1329–1339View ArticleGoogle Scholar
- Grau G, Subramanian V (2016) Fully high-speed gravure printed, low-variability, high-performance organic polymer transistors with sub-5 v operation. Adv Electron Mater 2(4):1500328View ArticleGoogle Scholar
- Yan H, Chen Z, Zheng Y, Newman C, Quinn JR, Dotz F, Kastler M, Facchetti A (2009) A high-mobility electron-transporting polymer for printed transistors. Nature 457(7230):679View ArticleGoogle Scholar
- Yu X, Zhou N, Han S, Lin H, Buchholz DB, Yu J, Chang RPH, Facchetti A (2013) Flexible spray-coated TIPS-pentacene organic thin-film transistors as ammonia gas sensors. J Mater Chem C 1(40):6532–6535View ArticleGoogle Scholar
- Pitsalidis C, Pappa AM, Hunter S, Laskarakis A, Kaimakamis T, Payne MM, Anthony JE, Anthopoulos TD, Logothetidis S (2016) High mobility transistors based on electrospray-printed small-molecule/polymer semiconducting blends. J Mater Chem C 4(16):3499–3507View ArticleGoogle Scholar
- Khim D, Baeg KJ, Yu BK, Kang SJ, Kang M, Chen Z, Facchetti A, Kim D, Noh YY (2013) Spray-printed organic field-effect transistors and complementary inverters. J Mater Chem C 1(7):1500–1506View ArticleGoogle Scholar
- Vak D, Kim SS, Jo J, Oh SH, Na SI, Kim J, Kim DY (2007) Fabrication of organic bulk heterojunction solar cells by a spray deposition method for low-cost power generation. Appl Phys Lett 91(8):081102View ArticleGoogle Scholar
- Susanna G, Salamandra L, Brown TM, Di Carlo A, Brunetti F, Reale A (2011) Airbrush spray-coating of polymer bulk-heterojunction solar cells. Sol Energ Mat Sol C 95(7):1775–1778View ArticleGoogle Scholar
- Ma W, Yang C, Gong X, Lee K, Heeger AJ (2005) Thermally stable, efficient polymer solar cells with nanoscale control of the interpenetrating network morphology. Adv Funct Mater 15(10):1617–1622View ArticleGoogle Scholar
- Park HY, Yang H, Choi SK, Jang SY (2011) Efficient solvent-assisted post-treatment for molecular rearrangement of sprayed polymer field-effect transistors. ACS Appl Mater Interfaces 4(1):214–221View ArticleGoogle Scholar
- Zhang P, Li S, Liu C, Wei X, Wu Z, Jiang Y, Chen Z (2014) Near-infrared optical absorption enhanced in black silicon via Ag nanoparticle-induced localized surface plasmon. Nanoscale Res Lett 9(1):519View ArticleGoogle Scholar
- Cheng H, Wang D, Li FL (2017) Effect of temperature on the microstructure and electrical conductivity of microcrystalline Si films. Mater Sci Forum 895:28–32View ArticleGoogle Scholar
- Sarcletti M, Schmaltz T, Halik M (2014) The mutual influence of surface energy and substrate temperature on the saturation mobility in organic semiconductors. Org Electron 15(11):3082–3086View ArticleGoogle Scholar
- Padma N, Maheshwari P, Bhattacharya D, Tokas RB, Sen S, Honda Y, Basu S, Pujari PK, Rao TC (2016) Investigations on substrate temperature-induced growth modes of organic semiconductors at dielectric/semiconductor interface and their correlation with threshold voltage stability in organic field-effect transistors. ACS Appl Mater Interfaces 8(5):3376–3385View ArticleGoogle Scholar
- Mikayelyan E, Vladimirov I, Wesner D, Grodd L, Rodygin AI, Schönherr H, Ponomarenko SA, Pietsch U, Ivanov DA, Grigorian S (2016) Impact of substrate temperature on the structure and electrical performance of vacuum-deposited α, α′-DH5T oligothiophene thin films. RSC Adv 6(116):115085–115091View ArticleGoogle Scholar
- Bae JH, Park J, Keum CM, Kim WH, Kim MH, Kim SO, Kwon SK, Lee SD (2010) Thermal annealing effect on the crack development and the stability of 6, 13-bis (triisopropylsilylethynyl)-pentacene field-effect transistors with a solution-processed polymer insulator. Org Electron 11(5):784–788View ArticleGoogle Scholar
- Zhuang X, Huang W, Yang X, Han S, Li L, Yu J (2016) Biocompatible/degradable silk fibroin: poly (vinyl alcohol)-blended dielectric layer towards high-performance organic field-effect transistor. Nanoscale Res Lett 11(1):439View ArticleGoogle Scholar
- Chou LH, Chang WC, He GY, Chiu YC, Liu CL (2016) Controllable electrical performance of spray-coated semiconducting small molecule/insulating polymer blend thin film for organic field effect transistors application. React Funct Polym 108:130–136View ArticleGoogle Scholar
- Basu S, Lee MC, Wang YH (2014) Graphene-based electrodes for enhanced organic thin film transistors based on pentacene. Phys Chem Chem Phys 16(31):16701–16710View ArticleGoogle Scholar
- Shi W, Han S, Huang W, Yu J (2015) High mobility organic field-effect transistor based on water-soluble deoxyribonucleic acid via spray coating. Appl Phys Lett 106(4)Google Scholar
- Sele CW, Kjellander BK, Niesen B, Thornton MJ, Van der Putten JBPH, Myny K, Wondergem HJ, Moser A, Resel R, Van Breemen AJM, Van Aerle N, Heremans P, Anthony JE, Gelinck GH (2009) Controlled deposition of highly ordered soluble acene thin films: effect of morphology and crystal orientation on transistor performance. Adv Mater 21(48):4926–4931View ArticleGoogle Scholar
- Li S, Zhang P, Chen H, Wang Y, Liu D, Wu J, Sarvari H, Chen ZD (2017) Mesoporous PbI2 assisted growth of large perovskite grains for efficient perovskite solar cells based on ZnO nanorods. J Power Sources 342:990–997View ArticleGoogle Scholar
- Kim Y, Jeon D (2017) Real time monitoring of ordering in pentacene films during growth by using in-situ infrared spectroscopy. Curr Appl Phys 17(7):972–975View ArticleGoogle Scholar
- Zheng Y, Wu R, Shi W, Guan Z, Yu J (2013) Effect of in situ annealing on the performance of spray coated polymer solar cells. Sol Energ Mat Sol C 111:200–205View ArticleGoogle Scholar
- Huang Y, Kramer EJ, Heeger AJ, Bazan GC (2014) Bulk heterojunction solar cells: morphology and performance relationships. Chem Rev 114(14):7006–7043View ArticleGoogle Scholar
- Mukherjee S, Proctor CM, Tumbleston JR, Bazan GC, Nguyen TQ, Ade H (2015) Importance of domain purity and molecular packing in efficient solution-processed small-molecule solar cells. Adv Mater 27(6):1105–1111View ArticleGoogle Scholar
- Yoo H, Choi HH, Shin TJ, Rim T, Cho K, Jung S, Kim JJ (2015) Self-assembled, millimeter-sized Tips-pentacene spherulites grown on partially crosslinked polymer gate dielectric. Adv Funct Mater 25(24):3658–3665View ArticleGoogle Scholar
- Grieco C, Doucette GS, Pensack RD, Payne MM, Rimshaw A, Scholes GD, Anthony JE, Asbury JB (2016) Dynamic exchange during triplet transport in nanocrystalline tips-pentacene films. J Am Chem Soc 138(49):16069–16080View ArticleGoogle Scholar
- Chen J, Anthony J, Martin DC (2006) Thermally induced solid-state phase transition of bis (triisopropylsilylethynyl) pentacene crystals. J Phys Chem B 110(33):16397–16403View ArticleGoogle Scholar
- Zhai L, Khondaker SI, Thomas J, Shen C, McInnis M (2014) Ordered conjugated polymer nano-and microstructures: structure control for improved performance of organic electronics. Nano Today 9(6):705–721View ArticleGoogle Scholar