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Energy level determination in bulk heterojunction systems using photoemission yield spectroscopy: case of P3HT:PCBM

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Abstract

Ultraviolet photoelectron spectroscopy (UPS) is commonly used method for energy level determination using planar heterojunction samples in either metal/organic or organic/organic systems. Only some attempts have been made in the study of bulk heterojunction systems. Photoemission yield spectroscopy (PYS) could be applied as a method for organic compound–organic compound interface studies in bulk heterojunction samples. Contrary to the UPS, PYS method does not require ultra-high vacuum, which simplifies experiment setup. Also, scanning depth of PYS is in the range of tens of nanometers, which allows studying deeper layers of the sample instead of only surface layer. In this work, poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) bulk heterojunction thin films were studied as a model system. A mass ratio between P3HT and PCBM in the system was varied from 1:0 to 1:50. Ionization energy dependence on this ratio was studied using two methods: UPS and PYS. To study the influence of the sample morphology on the PYS measurements and obtainable results, phase-separated and homogeneously distributed samples were prepared for analyses. P3HT ionization energy shift of 0.40 eV was observed in the samples made from chloroform solution. Experiments showed the need for a low degree of phase separation between P3HT and PCBM to observe P3HT ionization energy shift using PYS. On the contrary, no ionization energy shift of P3HT was observed in the UPS measurements for the same systems.

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References

  1. To CH, Wong FL, Lee CS, Zapien JA (2013) Transmission optimization of multilayer OLED encapsulation based on spectroscopic ellipsometry. Thin Solid Films 549:22–29. https://doi.org/10.1016/j.tsf.2013.07.018

    Article  Google Scholar 

  2. Cho AR, Kim EH, Park SY, Park LS (2014) Flexible OLED encapsulated with a gas barrier film and adhesive gasket. Synth Met 193:77–80. https://doi.org/10.1016/j.synthmet.2014.03.027

    Article  Google Scholar 

  3. Lee J, Yoshikawa S, Sagawa T (2014) Fabrication of efficient organic and hybrid solar cells by fine channel mist spray coating. Sol Energy Mater Sol Cells 127:111–121. https://doi.org/10.1016/j.solmat.2014.04.010

    Article  Google Scholar 

  4. Albrecht S, Grootoonk B, Neubert S et al (2014) Efficient hybrid inorganic/organic tandem solar cells with tailored recombination contacts. Sol Energy Mater Sol Cells 127:157–162. https://doi.org/10.1016/j.solmat.2014.04.020

    Article  Google Scholar 

  5. Wang H, Ji Z, Shang L et al (2011) Nonvolatile nano-crystal floating gate OFET memory with light assisted program. Org Electron 12:1236–1240. https://doi.org/10.1016/j.orgel.2011.03.037

    Article  Google Scholar 

  6. Cocchi M (2013) Organic light-emitting diodes (OLEDs). Org Light Diodes Mater Dev Appl. https://doi.org/10.1533/9780857098948.2.293

    Google Scholar 

  7. Xiao J, Liu X-K, Wang X-X et al (2014) Tailoring electronic structure of organic host for high-performance phosphorescent organic light-emitting diodes. Org Electron 15:2763–2768. https://doi.org/10.1016/j.orgel.2014.08.006

    Article  Google Scholar 

  8. Song S, Kim T, Bang SY et al (2013) Synthesis of the novel 2,2-bithiophene-3,3-dicarboximide-based conjugated copolymers for OPVs. Synth Met 177:65–71. https://doi.org/10.1016/j.synthmet.2013.06.012

    Article  Google Scholar 

  9. Fan C, Yang P, Wang X et al (2011) Synthesis and organic photovoltaic (OPV) properties of triphenylamine derivatives based on a hexafluorocyclopentene “core”. Sol Energy Mater Sol Cells 95:992–1000. https://doi.org/10.1016/j.solmat.2010.12.010

    Article  Google Scholar 

  10. Song S, Ko S-J, Shin H et al (2013) Pyrrolo[3,2-b]pyrrole based small molecules as donor materials for OPVs. Sol Energy Mater Sol Cells 112:120–126. https://doi.org/10.1016/j.solmat.2013.01.004

    Article  Google Scholar 

  11. Hayashi N, Ishii H, Ouchi Y, Seki K (2003) Examination of band bending at C60/metal interfaces by the Kelvin probe method. Synth Met 137:1377–1378. https://doi.org/10.1016/S0379-6779(02)01149-9

    Article  Google Scholar 

  12. Ito E, Oji H, Hayashi N et al (2001) Electronic structures of TPD/metal interfaces studied by photoemission and Kelvin probe method. Appl Surf Sci 176:407–411. https://doi.org/10.1016/S0169-4332(01)00088-5

    Article  Google Scholar 

  13. Beerbom MM, Lägel B, Cascio AJ et al (2006) Direct comparison of photoemission spectroscopy and in situ Kelvin probe work function measurements on indium tin oxide films. J Electron Spec Relat Phenom 152:12–17. https://doi.org/10.1016/j.elspec.2006.02.001

    Article  Google Scholar 

  14. Gao Y (2010) Surface analytical studies of interfaces in organic semiconductor devices. Mater Sci Eng R Rep 68:39–87. https://doi.org/10.1016/j.mser.2010.01.001

    Article  Google Scholar 

  15. Tang JX, Tong SW, Lee CS et al (2003) Photoemission study of interface formation between ytterbium and tris-(8-hydroxyquinoline) aluminum. Chem Phys Lett 380:63–69. https://doi.org/10.1016/j.cplett.2003.08.088

    Article  Google Scholar 

  16. Schwieger T, Peisert H, Knupfer M (2004) Direct observation of interfacial charge transfer from silver to organic semiconductors. Chem Phys Lett 384:197–202. https://doi.org/10.1016/j.cplett.2003.11.094

    Article  Google Scholar 

  17. Park M, Woong J (2017) Anthracene-based perylene diimide electron-acceptor for fullerene-free organic solar cells. Dye Pigment 143:301–307. https://doi.org/10.1016/j.dyepig.2017.04.057

    Article  Google Scholar 

  18. Rybakiewicz R, Gawrys P, Tsikritzis D et al (2013) Electronic properties of semiconducting naphthalene bisimide derivatives—Ultraviolet photoelectron spectroscopy versus electrochemistry. Electrochim Acta 96:13–17. https://doi.org/10.1016/j.electacta.2013.02.041

    Article  Google Scholar 

  19. Salaneck WR (2009) Classical ultraviolet photoelectron spectroscopy of polymers. J Electron Spec Relat Phenom 174:3–9. https://doi.org/10.1016/j.elspec.2009.03.024

    Article  Google Scholar 

  20. Braun S, Salaneck WR, Fahlman M (2009) Energy-level alignment at organic/metal and organic/organic interfaces. Adv Mater 21:1450–1472. https://doi.org/10.1002/adma.200802893

    Article  Google Scholar 

  21. Xu Z, Chen L-M, Chen M-H et al (2009) Energy level alignment of poly(3-hexylthiophene): [6]-phenyl C[sub 61] butyric acid methyl ester bulk heterojunction. Appl Phys Lett 95:013301. https://doi.org/10.1063/1.3163056

    Article  Google Scholar 

  22. Tsoi WC, Spencer SJ, Yang L et al (2011) Effect of crystallization on the electronic energy levels and thin film morphology of P3HT:PCBM blends. Macromolecules 44:2944–2952. https://doi.org/10.1021/ma102841e

    Article  Google Scholar 

  23. Guan Z-L, Kim JB, Wang H et al (2010) Direct determination of the electronic structure of the poly(3-hexylthiophene):phenyl-[6]-C61 butyric acid methyl ester blend. Org Electron 11:1779–1785. https://doi.org/10.1016/j.orgel.2010.07.023

    Article  Google Scholar 

  24. El-Sayed A, Borghetti P, Goiri E et al (2013) Understanding energy-level alignment in donor à acceptor/metal interfaces from core-level shifts. ACS Nano 7:6914–6920. https://doi.org/10.1021/nn4020888

    Article  Google Scholar 

  25. Aygul U, Hintz H, Egelhaaf H et al (2013) Energy level alignment of a P3HT/fullerene blend during the initial steps of degradation. J Phys Chem C 117:4992–4998. https://doi.org/10.1021/jp4004642

    Article  Google Scholar 

  26. Kanai K, Honda M, Ishii H et al (2012) Interface electronic structure between the organic semiconductor film and electrode metal probed by photoelectron yield spectroscopy. Org Electron 13:309–319. https://doi.org/10.1016/j.orgel.2011.11.024

    Article  Google Scholar 

  27. Honda M, Kanai K, Komatsu K et al (2007) Atmospheric effect of air, N[sub 2], O[sub 2], and water vapor on the ionization energy of titanyl phthalocyanine thin film studied by photoemission yield spectroscopy. J Appl Phys 102:103704. https://doi.org/10.1063/1.2809360

    Article  Google Scholar 

  28. Grigalevicius S, Blazys G (2002) 3, 6-Di (N-diphenylamino)-9-phenylcarbazole and its methyl-substituted derivative as novel hole-transporting amorphous molecular materials. Synth Met 128:127–131. https://doi.org/10.1016/S0379-6779(01)00546-X

    Article  Google Scholar 

  29. Seah M, Dench W (1979) Quantitative electron spectroscopy of surfaces: a standard database for electron inelastic mean free paths in solids. Surf Interface Anal 1:2–11. https://doi.org/10.1002/sia.740010103

    Article  Google Scholar 

  30. Monjushiro H, Watanabe I, Yokoyama Y (1991) Ultraviolet photoelectron yield spectra of thin gold films measured in air. Anal Sci 7:543–547. https://doi.org/10.2116/analsci.7.543

    Article  Google Scholar 

  31. Banoukepa GDR, Fujii A, Shimizu Y, Ozaki M (2015) 1,3,5-Tris(phenyl-2-benzimidazole)-benzene cathode buffer layer thickness dependence in solution-processable organic solar cell based on 1,4,8,11,15,18,22,25-octahexylphthalocyanine. Jpn J Appl Phys 11:4–9. https://doi.org/10.7567/JJAP.54.04DK11

    Google Scholar 

  32. Grzibovskis R, Vembris A (2016) Study of the P3HT/PCBM interface using photoemission yield spectroscopy. Proc SPIE 9895:98950Q. https://doi.org/10.1117/12.2227823

    Article  Google Scholar 

  33. Nam S, Shin M, Park S et al (2012) All-polymer solar cells with bulk heterojunction nanolayers of chemically doped electron-donating and electron-accepting polymers. Phys Chem Chem Phys 14:15046–15053. https://doi.org/10.1039/c2cp43002a

    Article  Google Scholar 

  34. Lu Y, Wang Y, Feng Z et al (2012) Temperature-dependent morphology evolution of P3HT:PCBM blend solar cells during annealing processes. Synth Met 162:2039–2046. https://doi.org/10.1016/j.synthmet.2012.10.012

    Article  Google Scholar 

  35. Fukuda T, Toda A, Takahira K et al (2016) Molecular ordering of spin-coated and electrosprayed P3HT:PCBM thin films and their applications to photovoltaic cell. Thin Solid Films 612:373–380. https://doi.org/10.1016/j.tsf.2016.06.019

    Article  Google Scholar 

  36. Baek W-H, Yang H, Yoon T-S et al (2009) Effect of P3HT:PCBM concentration in solvent on performances of organic solar cells. Sol Energy Mater Sol Cells 93:1263–1267. https://doi.org/10.1016/j.solmat.2009.01.019

    Article  Google Scholar 

  37. Shen Y, Li K, Majumdar N et al (2011) Bulk and contact resistance in P3HT:PCBM heterojunction solar cells. Sol Energy Mater Sol Cells 95:2314–2317. https://doi.org/10.1016/j.solmat.2011.03.046

    Article  Google Scholar 

  38. Baek W-H, Yoon T-S, Lee HH, Kim Y-S (2010) Composition-dependent phase separation of P3HT:PCBM composites for high performance organic solar cells. Org Electron 11:933–937. https://doi.org/10.1016/j.orgel.2010.02.013

    Article  Google Scholar 

  39. Chen S, Zeng W, Su X et al (2015) Effect of preparation parameters on performance of P3HT:PCBM solar cells. Mater Sci Semicond Process 39:441–446. https://doi.org/10.1016/j.mssp.2015.05.001

    Article  Google Scholar 

  40. Müllerová J, Kaiser M, Nádaždy V et al (2016) Optical absorption study of P3HT:PCBM blend photo-oxidation for bulk heterojunction solar cells. Sol Energy 134:294–301. https://doi.org/10.1016/j.solener.2016.05.009

    Article  Google Scholar 

  41. Grzibovskis R, Vembris A, Pudzs K (2016) Relation between molecule ionization energy, film thickness and morphology of two indandione derivatives thin films. J Phys Chem Solids 95:12–18. https://doi.org/10.1016/j.jpcs.2016.03.010

    Article  Google Scholar 

  42. Xu Z, Chen L-M, Yang G et al (2009) Vertical phase separation in Poly(3-hexylthiophene): fullerene derivative blends and its advantage for inverted structure solar cells. Adv Funct Mater 19:1227–1234. https://doi.org/10.1002/adfm.200801286

    Article  Google Scholar 

  43. Swinnen A, Haeldermans I, van de Ven M et al (2006) Tuning the Dimensions of C60-Based Needlelike Crystals in Blended Thin Films. Adv Funct Mater 16:760–765

    Article  Google Scholar 

  44. Dang MT, Wantz G, Bejbouji H et al (2011) Polymeric solar cells based on P3HT:PCBM: Role of the casting solvent. Sol Energy Mater Sol Cells 95:3408–3418. https://doi.org/10.1016/j.solmat.2011.07.039

    Article  Google Scholar 

  45. Kane EO (1962) Theory of photoelectric emission from semiconductors. Phys Rev 127:131–141

    Article  Google Scholar 

  46. Ow-Yang CW, Jia J, Aytun T et al (2014) Work function tuning of tin-doped indium oxide electrodes with solution-processed lithium fluoride. Thin Solid Films 559:58–63. https://doi.org/10.1016/j.tsf.2013.11.035

    Article  Google Scholar 

  47. Ozawa Y, Nakayama Y, Machida S et al (2014) Maximum probing depth of low-energy photoelectrons in an amorphous organic semiconductor film. J Electron Spectros Relat Phenom 197:17–21. https://doi.org/10.1016/j.elspec.2014.08.001

    Article  Google Scholar 

  48. Aarnio H, Sehati P, Braun S et al (2011) Spontaneous charge transfer and dipole formation at the interface between P3HT and PCBM HOMO. Adv Energy Mater. https://doi.org/10.1002/aenm.201100074

    Google Scholar 

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Acknowledgements

Financial support provided by Scientific Research Project for Students and Young Researchers Nr. SJZ2015/20 realized at the Institute of Solid State Physics, University of Latvia, is greatly acknowledged. This work has been supported by the Latvian State Research Program on Multifunctional Materials IMIS2. Jennifer Mann from Physical Electronics is greatly acknowledged for providing UPS data.

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Correspondence to Raitis Grzibovskis.

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Grzibovskis, R., Vembris, A. Energy level determination in bulk heterojunction systems using photoemission yield spectroscopy: case of P3HT:PCBM. J Mater Sci 53, 7506–7515 (2018). https://doi.org/10.1007/s10853-018-2050-9

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