Beating the thermodynamic limit with photo-activation of n-doping in organic semiconductors
Source abstract
Abstract
Chemical doping of organic semiconductors using molecular dopants plays a key role in the fabrication of efficient organic electronic devices. Although a variety of stable molecular p-dopants have been developed and successfully deployed in devices in the past decade, air-stable molecular n-dopants suitable for materials with low electron affinity are still elusive. Here we demonstrate that photo-activation of a cleavable air-stable dimeric dopant can result in kinetically stable and efficient n-doping of host semiconductors, whose reduction potentials are beyond the thermodynamic reach of the dimer's effective reducing strength. Electron-transport layers doped in this manner are used to fabricate high-efficiency organic light-emitting diodes. Our strategy thus enables a new paradigm for using air-stable molecular dopants to improve conductivity in, and provide ohmic contacts to, organic semiconductors with very low electron affinity.
Source: europepmc · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Organic Electronics and Photovoltaics · Organic Light-Emitting Diodes Research · Molecular Junctions and Nanostructures
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (43)
Show source-provided references
1. Lüssem, B., Riede, M. & Leo, K. Doping of organic semiconductors. Phys. Status Solidi A 210, 9–43 (2013).10.1002/pssa.201228310 ↗
2. Salzmann, I. & Heimel, G. Toward a comprehensive understanding of molecular doping organic semiconductors (review). J. Electron Spectrosc. Relat. Phenom. 204, 208–222 (2015).10.1016/j.elspec.2015.05.001 ↗
3. Reineke, S. et al. White organic light-emitting diodes with fluorescent tube efficiency. Nature 459, 234–239 (2009).10.1038/nature08003 ↗
4. Murawski, C., Fuchs, C., Hofmann, S., Leo, K. & Gather, M. C. Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes. Appl. Phys. Lett. 105, 113303 (2014).10.1063/1.4896127 ↗
5. Selzer, F. et al. Improved organic p-i-n type solar cells with n-doped fluorinated hexaazatrinaphthylene derivatives HATNA-F6 and HATNA-F12 as transparent electron transport material. J. Appl. Phys. 115, 54515 (2014).10.1063/1.4864260 ↗
6. Lei, X., Zhang, F., Song, T. & Sun, B. p-type doping effect on the performance of organic-inorganic hybrid solar cells. Appl. Phys. Lett. 99, 233305 (2011).10.1063/1.3669393 ↗
7. Lüssem, B. et al. Doped organic transistors operating in the inversion and depletion regime. Nat. Commun. 4, 2775 (2013).10.1038/ncomms3775 ↗
8. Ma, L. et al. High performance polythiophene thin-film transistors doped with very small amounts of an electron acceptor. Appl. Phys. Lett. 92, 63310 (2008).10.1063/1.2883927 ↗
9. Naab, B. D. et al. High mobility N-type transistors based on solution- sheared doped 6,13-Bis(triisopropylsilylethynyl)pentacene thin films. Adv. Mater. 25, 4663–4667 (2013).10.1002/adma.201205098 ↗
10. Olthof, S. et al. Passivation of trap states in unpurified and purified C60 and the influence on organic field-effect transistor performance. Appl. Phys. Lett. 101, 253303 (2012).10.1063/1.4772551 ↗
11. Oh, J. H., Wei, P. & Bao, Z. Molecular n-type doping for air-stable electron transport in vacuum-processed n-channel organic transistors. Appl. Phys. Lett. 97, 243305 (2010).10.1063/1.3527972 ↗
12. Tang, C. G. et al. Doped polymer semiconductors with ultrahigh and ultralow work functions for ohmic contacts. Nature 539, 536–540 (2016).10.1038/nature20133 ↗
13. Kulkarni, A. P., Tonzola, C. J., Babel, A. & Jenekhe, S. A. Electron transport materials for organic light-emitting diodes. Chem. Mater. 16, 4556–4573 (2004).10.1021/cm049473l ↗
14. Chan, C. K., Kim, E. G., Brédas, J.-L. & Kahn, A. Molecular n-type doping of 1,4,5,8-naphthalene tetracarboxylic dianhydride by pyronin B studied using direct and inverse photoelectron spectroscopies. Adv. Funct. Mater. 16, 831–837 (2006).10.1002/adfm.200500402 ↗
15. Werner, A. G. et al. Pyronin B as a donor for n-type doping of organic thin films. Appl. Phys. Lett. 82, 4495–4497 (2003).10.1063/1.1583872 ↗
16. Li, F., Werner, A., Pfeiffer, M., Leo, K. & Liu, X. Leuco crystal violet as a dopant for n-doping of organic thin films of fullerene C60 . J. Phys. Chem. B 108, 17076–17082 (2004).10.1021/jp0478615 ↗
17. Li, F. et al. Acridine orange base as a dopant for n doping of C60 thin films. J. Appl. Phys. 100, 1–9 (2006).10.1007/11378235_1 ↗
18. Wei, P. et al. 2-(2-Methoxyphenyl)-1,3-dimethyl-1H-benzoimidazol-3-ium iodide as a new air-stable n-type dopant for vacuum-processed organic semiconductor thin films. J. Am. Chem. Soc. 134, 3999–4002 (2012).10.1021/ja211382x ↗
19. Wei, P., Oh, J. H., Dong, G. & Bao, Z. Use of a 1H-benzoimidazole derivative as an n-type dopant and to enable air-stable solution-processed n-channel organic thin-film transistors. J. Am. Chem. Soc. 132, 8852–8853 (2010).10.1021/ja103173m ↗
20. Schlitz, R. A. et al. Solubility-limited extrinsic n-type doping of a high electron mobility polymer for thermoelectric applications. Adv. Mater. 26, 2825–2830 (2014).10.1002/adma.201304866 ↗
21. Naab, B. D. et al. Effective solution- and vacuum-processed n-doping by dimers of benzimidazoline radicals. Adv. Mater. 26, 4268–4272 (2014).10.1002/adma.201400668 ↗
22. Rossbauer, S., Müller, C. & Anthopoulos, T. D. Comparative study of the n-type doping efficiency in solution-processed fullerenes and fullerene derivatives. Adv. Funct. Mater. 24, 7116–7124 (2014).10.1002/adfm.201401842 ↗
23. Naab, B. D. et al. Mechanistic study on the solution-phase n-doping of 1,3-dimethyl-2-aryl-2,3-dihydro-1H-benzoimidazole derivatives. J. Am. Chem. Soc. 135, 15018–15025 (2013).10.1021/ja403906d ↗
24. Zhang, Y., de Boer, B. & Blom, P. W. M. Trap-free electron transport in poly(p-phenylene vinylene) by deactivation of traps with n-type doping. Phys. Rev. B 81, 85201 (2010).10.1103/PhysRevB.81.085201 ↗
25. Weber, C. D., Bradley, C. & Lonergan, M. C. Solution phase n-doping of C60 and PCBM using tetrabutylammonium fluoride. J. Mater. Chem. A 2, 303–307 (2014).10.1039/C3TA14132B ↗
26. Guo, S. et al. n-doping of organic electronic materials using air-stable organometallics: a mechanistic study of reduction by dimeric sandwich compounds. Chem. Eur. J. 18, 14760–14772 (2012).10.1002/chem.201202591 ↗
27. Guo, S. et al. n-doping of organic electronic materials using air-stable organometallics. Adv. Mater. 24, 699–703 (2012).10.1002/adma.201103238 ↗
28. Qi, Y. et al. Solution doping of organic semiconductors using air-stable n-dopants. Appl. Phys. Lett. 100, 83305 (2012).10.1063/1.3689760 ↗
29. Olthof, S. et al. Ultralow doping in organic semiconductors: evidence of trap filling. Phys. Rev. Lett. 109, 176601 (2012).10.1103/PhysRevLett.109.176601 ↗
30. Higgins, A., Mohapatra, S. K., Barlow, S., Marder, S. R. & Kahn, A. Dopant controlled trap-filling and conductivity enhancement in an electron-transport polymer. Appl. Phys. Lett. 106, 163301 (2015).10.1063/1.4918627 ↗
31. Mohapatra, S. K. et al. Dimers of nineteen-electron sandwich compounds: crystal and electronic structures, and comparison of reducing strengths. Chem. Eur. J. 20, 15385–15394 (2014).10.1002/chem.201404007 ↗
32. Walzer, K., Maennig, B., Pfeiffer, M. & Leo, K. Highly efficient organic devices based on electrically doped transport layers. Chem. Rev. 107, 1233–1271 (2007).10.1021/cr050156n ↗
33. Oyamada, T. et al. Extremely low-voltage driving of organic light-emitting diodes with a Cs-doped phenyldipyrenylphosphine oxide layer as an electron-injection layer. Appl. Phys. Lett. 86, 33503 (2005).10.1063/1.1852707 ↗
34. Matsushima, T. & Adachi, C. High-current injection and transport on order of kA/cm2 in organic light-emitting diodes having mixed organic/organic heterojunction interfaces. Jpn. J. Appl. Phys. 46, L861–L863 (2007).10.1143/JJAP.46.L861 ↗
35. Matsushima, T. & Adachi, C. Suppression of exciton annihilation at high current densities in organic light-emitting diode resulting from energy-level alignments of carrier transport layers. Appl. Phys. Lett. 92, 63306 (2008).10.1063/1.2844891 ↗
36. Yoshida, H. & Yoshizaki, K. Electron affinities of organic materials used for organic light-emitting diodes: a low-energy inverse photoemission study. Org. Electron. 20, 24–30 (2015).10.1016/j.orgel.2015.01.037 ↗
37. Choi, J. M. & Lee, J. Y. Triplet emitter doped exciton harvesting layer for improved efficiency and long lifetime in blue phosphorescent organic light-emitting diodes. Synth. Met. 220, 573–577 (2016).10.1016/j.synthmet.2016.07.033 ↗
38. Hiszpanski, A. M. et al. Halogenation of a nonplanar molecular semiconductor to tune energy levels and bandgaps for electron transport. Chem. Mater. 27, 1892–1900 (2015).10.1021/acs.chemmater.5b00329 ↗
39. Davy, N. C. et al. Contorted hexabenzocoronenes with extended heterocyclic moieties improve visible-light absorption and performance in organic solar cells. Chem. Mater. 28, 673–681 (2016).10.1021/acs.chemmater.5b04503 ↗
40. Pommerehne, J. et al. Efficient two layer LEDs on a polymer blend basis. Adv. Mater. 7, 551–554 (1995).10.1002/adma.19950070608 ↗
41. Tao, Y. T., Balasubramaniam, E., Danel, A. & Tomasik, P. Dipyrazolopyridine derivatives as bright blue electroluminescent materials. Appl. Phys. Lett. 77, 933–935 (2000).10.1063/1.1288811 ↗
42. Swensen, J. S. et al. Improved efficiency in blue phosphorescent organic light-emitting devices using host materials of lower triplet energy than the phosphorescent blue emitter. Adv. Funct. Mater. 21, 3250–3258 (2011).10.1002/adfm.201100586 ↗
43. Wu, C. I., Hirose, Y., Sirringhaus, H. & Kahn, A. Electron-hole interaction energy in the organic molecular semiconductor PTCDA. Chem. Phys. Lett. 272, 43–47 (1997).10.1016/S0009-2614(97)00481-8 ↗