- Email: [email protected]
Some aspects of oxide and organic semiconductors
Current Opinion in Solid State and Materials Science 11 (2007) 1–2
Contents lists available at ScienceDirect
Current Opinion in Solid State and Materials Science journal homepage: www.elsevier.com/locate/cossms
Editorial overview
Some aspects of oxide and organic semiconductors
Three of the nine research targets in energy related research identified by the US Department of Energy’s workshop on Nanoscience for Energy Needs [1] were (i) scalable methods to split water with sunlight for hydrogen production, (ii) harvesting solar energy with 20% power efficiency and 100 times lower cost, and (iii) solid-state lighting with a power consumption 50% of current usage. Organic and oxide semiconductors, particularly thin film and nanostructured forms of these materials, are actively being investigated to meet these challenges. A significant event was the demonstration by Schmuki, Macak and co-workers of the formation of a range of porous oxides and tubular oxide films, for example, Ta2O5 [2], TiO2 [3–5], WO3 [6] and ZrO2 [7] produced by means of electrochemical etching of valve metals. Oxide nanowires have also been produced by catalytic growth, including the vapor–liquid–solid (VLS) mechanism and its variants [8]. TiO2 is a material of special interest because of its possible applications in photocatalysis (including photocatalytic hydrogen production), drug delivery and as a biocompatible material. The use of titania nanotubes in solar energy applications has been reviewed [9]. A variety of other methods has been demonstrated to produce TiO2 nanotubes or nanofibers including template-directed synthesis [10], electrospinning [11], and sol–gel coating of polymer fibers [12]. In this issue, Macak et al. provide an insightful review of their recent work to produce nanostructured titania films by means of electrochemical etching in fluoride solutions. Gas sensing is another application for which semiconducting oxides are highly sought [13,14]. Not only TiO2 but also other oxides such as ZnO, SnO2, In2O3 and Ga2O3 have been investigated, particularly in quasi-one-dimensional structures such as nanowires and nanotubes [15]. The search for new materials continues and Kanan and Tripp [16] write in this issue about the synthesis, characterication and use of WO3 as a gas sensor. They discuss methods to produce both nonporous and nanoscale porous monoclinic WO3 powders as well as particle size dependence in sensing capabilities. Organic light-emitting devices (OLEDs) have been studied for some time because of their electroluminescent properties and potential application in flat panel displays [17,18]. Both small molecule and polymer organics have been investigated. The search for new materials continues as does research to find ways to increase efficiency, lifetime and color coverage by using novel architectures, processing methods and additives. Solution processable polymers – either in the form of fluorescent conjugated polymers or phosphorescent dye-dispersed nonconjugated polymers [17] – have particular advantages when it comes to low cost fabrication of large area 1359-0286/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.cossms.2008.04.003
devices. Blends of conjugated polymers can exhibit morphologies that enhance their electroluminescent properties [18]. More recently, it has been recognized that white organic light-emitting devices (WOLEDs) may play an important role in the development of more efficient solid-state lighting because they can now exhibit power efficiencies superior to those of incandescent light sources [19,20]. Chen and co-workers [21] provide a brief introduction to WOLEDs and present some new results on a carbazolyl–vinyl–phenyl–fluorene polymer (F-CZV), a white light-emitting polymer whose color is close to independent of the driving voltage.
References [1] Alivisatos AP, Majundar A, Cummings P, Makowski L, De Yoreo JJ, Misewich J, Fichthorn K, Murray C, Gates BC, Sibener S, Hwang R, Teague C, Lowdnes D, Williams E. Nanoscience research for energy needs: report of the March 2004 National Nanotechnology Initiative Grand Challenge Workshop, National Nanotechnology Coordination Office and Department of Energy (US), Office of Basic Energy Sciences; 2005. [2] Sieber IV, Schmuki P. Porous tantalum oxide prepared by electrochemical anodic oxidation. J Electrochem Soc 2005;152:C639–44. [3] Beranek R, Hildebrand H, Schmuki P. Self-organized porous titanium oxide prepared in H2SO4/HF electrolytes. Electrochem Solid State Lett 2003;6:B12–4. [4] Macak JM, Tsuchiya H, Taveira L, Aldabergerova S, Schmuki P. Smooth anodic TiO2 nanotubes. Angew Chem, Int Ed Engl 2005;44:7463–5. [5] Macak JM, Tsuchiya H, Schmuki P. High-aspect-ratio TiO2nanotubes by anodization of titanium. Angew Chem, Int Ed Engl 2005;44:2100–2. [6] Tsuchiya H, Macak JM, Sieber I, Taveira L, Ghicov A, Sirotna K, et al. Selforganized porous WO3 formed in NaF electrolytes. Electrochem Commun 2005;7:295–8. [7] Tsuchiya H, Macak JM, Taveira L, Schmuki P. Fabrication and characterization of smooth high aspect ratio zirconia nanotubes. Chem Phys Lett 2005;410:188–91. [8] Kolasinski KW. Catalytic growth of nanowires: vapor–liquid–solid, vapor– solid–solid, solution–liquid–solid and solid–liquid–solid growth. Curr Opin Solid State Mater Sci 2006;10:182–91. [9] Mor GK, Varghese OK, Paulose M, Shankar K, Grimes CA. A review on highly ordered, vertically oriented TiO2 nanotube arrays: fabrication, material properties, and solar energy applications. Sol Energy Mater 2006;90:2011–75. [10] Bae C, Yoo H, Kim S, Lee K, Kim J, Sung MA, et al. Template-directed synthesis of oxide nanotubes: fabrication, characterization, and applications. Chem Mater 2008;20:756–67. [11] Li D, Xia YN. Fabrication of titania nanofibers by electrospinning. NanoLetters 2003;3:555–60. [12] Caruso RA, Schattka JH, Greiner A. Titanium dioxide tubes from sol–gel coating of electrospun polymer fibers. Adv Mater 2001;13:1577–9. [13] Fleischer M. Advances in application potential of adsorptive-type solid state gas sensors: high-temperature semiconducting oxides and ambient temperature GasFET devices. Meas Sci Technol 2008;19:042001. [14] Barsan N, Koziej D, Weimar U. Metal oxide-based gas sensor research: How to? Sensor Actuator B 2007;121:18–35. [15] Lu JG, Chang PC, Fan ZY. Quasi-one-dimensional metal oxide materials – synthesis, properties and applications. Mater Sci Eng, R 2006;52:49–91. [16] Kanan SM, Tripp CP. Synthesis, FTIR studies and sensor properties of WO3 powders. Curr Opin Solid State Mater Sci 2007;11.
2
Editorial overview / Current Opinion in Solid State and Materials Science 11 (2007) 1–2
[17] So F, Krummacher B, Mathai MK, Poplavskyy D, Choulis SA, Choong VE. Recent progress in solution processable organic light emitting devices. J Appl Phys 2007;102:091101. [18] Moons E. Conjugated polymer blends: linking film morphology to performance of light emitting diodes and photodiodes. J Phys – Condens Mat 2002;14:12235–60. [19] Misra A, Kumar P, Kamalasanan MN, Chandra S. White organic LEDs and their recent advancements. Semicond Sci Technol 2006;21:R35–47. [20] D’Andrade BW, Forrest SR. White organic light-emitting devices for solid-state lighting. Adv Mater 2004;16:1585–95. [21] Chen Z, Feng L, Zhang C, Bie H, Lei G, Bai F. The light-emitting device consisting of organic white-light components. Curr Opin Solid State Mater Sci 2007;11.
Kurt W. Kolasinski Department of Chemistry, West Chester University, West Chester, PA 19383, USA, Fax: +1 610 436 2890 E-mail address: [email protected]
Contents lists available at ScienceDirect
Current Opinion in Solid State and Materials Science journal homepage: www.elsevier.com/locate/cossms
Editorial overview
Some aspects of oxide and organic semiconductors
Three of the nine research targets in energy related research identified by the US Department of Energy’s workshop on Nanoscience for Energy Needs [1] were (i) scalable methods to split water with sunlight for hydrogen production, (ii) harvesting solar energy with 20% power efficiency and 100 times lower cost, and (iii) solid-state lighting with a power consumption 50% of current usage. Organic and oxide semiconductors, particularly thin film and nanostructured forms of these materials, are actively being investigated to meet these challenges. A significant event was the demonstration by Schmuki, Macak and co-workers of the formation of a range of porous oxides and tubular oxide films, for example, Ta2O5 [2], TiO2 [3–5], WO3 [6] and ZrO2 [7] produced by means of electrochemical etching of valve metals. Oxide nanowires have also been produced by catalytic growth, including the vapor–liquid–solid (VLS) mechanism and its variants [8]. TiO2 is a material of special interest because of its possible applications in photocatalysis (including photocatalytic hydrogen production), drug delivery and as a biocompatible material. The use of titania nanotubes in solar energy applications has been reviewed [9]. A variety of other methods has been demonstrated to produce TiO2 nanotubes or nanofibers including template-directed synthesis [10], electrospinning [11], and sol–gel coating of polymer fibers [12]. In this issue, Macak et al. provide an insightful review of their recent work to produce nanostructured titania films by means of electrochemical etching in fluoride solutions. Gas sensing is another application for which semiconducting oxides are highly sought [13,14]. Not only TiO2 but also other oxides such as ZnO, SnO2, In2O3 and Ga2O3 have been investigated, particularly in quasi-one-dimensional structures such as nanowires and nanotubes [15]. The search for new materials continues and Kanan and Tripp [16] write in this issue about the synthesis, characterication and use of WO3 as a gas sensor. They discuss methods to produce both nonporous and nanoscale porous monoclinic WO3 powders as well as particle size dependence in sensing capabilities. Organic light-emitting devices (OLEDs) have been studied for some time because of their electroluminescent properties and potential application in flat panel displays [17,18]. Both small molecule and polymer organics have been investigated. The search for new materials continues as does research to find ways to increase efficiency, lifetime and color coverage by using novel architectures, processing methods and additives. Solution processable polymers – either in the form of fluorescent conjugated polymers or phosphorescent dye-dispersed nonconjugated polymers [17] – have particular advantages when it comes to low cost fabrication of large area 1359-0286/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.cossms.2008.04.003
devices. Blends of conjugated polymers can exhibit morphologies that enhance their electroluminescent properties [18]. More recently, it has been recognized that white organic light-emitting devices (WOLEDs) may play an important role in the development of more efficient solid-state lighting because they can now exhibit power efficiencies superior to those of incandescent light sources [19,20]. Chen and co-workers [21] provide a brief introduction to WOLEDs and present some new results on a carbazolyl–vinyl–phenyl–fluorene polymer (F-CZV), a white light-emitting polymer whose color is close to independent of the driving voltage.
References [1] Alivisatos AP, Majundar A, Cummings P, Makowski L, De Yoreo JJ, Misewich J, Fichthorn K, Murray C, Gates BC, Sibener S, Hwang R, Teague C, Lowdnes D, Williams E. Nanoscience research for energy needs: report of the March 2004 National Nanotechnology Initiative Grand Challenge Workshop, National Nanotechnology Coordination Office and Department of Energy (US), Office of Basic Energy Sciences; 2005. [2] Sieber IV, Schmuki P. Porous tantalum oxide prepared by electrochemical anodic oxidation. J Electrochem Soc 2005;152:C639–44. [3] Beranek R, Hildebrand H, Schmuki P. Self-organized porous titanium oxide prepared in H2SO4/HF electrolytes. Electrochem Solid State Lett 2003;6:B12–4. [4] Macak JM, Tsuchiya H, Taveira L, Aldabergerova S, Schmuki P. Smooth anodic TiO2 nanotubes. Angew Chem, Int Ed Engl 2005;44:7463–5. [5] Macak JM, Tsuchiya H, Schmuki P. High-aspect-ratio TiO2nanotubes by anodization of titanium. Angew Chem, Int Ed Engl 2005;44:2100–2. [6] Tsuchiya H, Macak JM, Sieber I, Taveira L, Ghicov A, Sirotna K, et al. Selforganized porous WO3 formed in NaF electrolytes. Electrochem Commun 2005;7:295–8. [7] Tsuchiya H, Macak JM, Taveira L, Schmuki P. Fabrication and characterization of smooth high aspect ratio zirconia nanotubes. Chem Phys Lett 2005;410:188–91. [8] Kolasinski KW. Catalytic growth of nanowires: vapor–liquid–solid, vapor– solid–solid, solution–liquid–solid and solid–liquid–solid growth. Curr Opin Solid State Mater Sci 2006;10:182–91. [9] Mor GK, Varghese OK, Paulose M, Shankar K, Grimes CA. A review on highly ordered, vertically oriented TiO2 nanotube arrays: fabrication, material properties, and solar energy applications. Sol Energy Mater 2006;90:2011–75. [10] Bae C, Yoo H, Kim S, Lee K, Kim J, Sung MA, et al. Template-directed synthesis of oxide nanotubes: fabrication, characterization, and applications. Chem Mater 2008;20:756–67. [11] Li D, Xia YN. Fabrication of titania nanofibers by electrospinning. NanoLetters 2003;3:555–60. [12] Caruso RA, Schattka JH, Greiner A. Titanium dioxide tubes from sol–gel coating of electrospun polymer fibers. Adv Mater 2001;13:1577–9. [13] Fleischer M. Advances in application potential of adsorptive-type solid state gas sensors: high-temperature semiconducting oxides and ambient temperature GasFET devices. Meas Sci Technol 2008;19:042001. [14] Barsan N, Koziej D, Weimar U. Metal oxide-based gas sensor research: How to? Sensor Actuator B 2007;121:18–35. [15] Lu JG, Chang PC, Fan ZY. Quasi-one-dimensional metal oxide materials – synthesis, properties and applications. Mater Sci Eng, R 2006;52:49–91. [16] Kanan SM, Tripp CP. Synthesis, FTIR studies and sensor properties of WO3 powders. Curr Opin Solid State Mater Sci 2007;11.
2
Editorial overview / Current Opinion in Solid State and Materials Science 11 (2007) 1–2
[17] So F, Krummacher B, Mathai MK, Poplavskyy D, Choulis SA, Choong VE. Recent progress in solution processable organic light emitting devices. J Appl Phys 2007;102:091101. [18] Moons E. Conjugated polymer blends: linking film morphology to performance of light emitting diodes and photodiodes. J Phys – Condens Mat 2002;14:12235–60. [19] Misra A, Kumar P, Kamalasanan MN, Chandra S. White organic LEDs and their recent advancements. Semicond Sci Technol 2006;21:R35–47. [20] D’Andrade BW, Forrest SR. White organic light-emitting devices for solid-state lighting. Adv Mater 2004;16:1585–95. [21] Chen Z, Feng L, Zhang C, Bie H, Lei G, Bai F. The light-emitting device consisting of organic white-light components. Curr Opin Solid State Mater Sci 2007;11.
Kurt W. Kolasinski Department of Chemistry, West Chester University, West Chester, PA 19383, USA, Fax: +1 610 436 2890 E-mail address: [email protected]