Tuning the colour and efficiency of OLEDs * *This chapter is dedicated to the memory of Professor Jan Kalinowski, who died on 18 December2010.

Cocchi, M.

doi:10.1533/9780857098948.2.293

Cited by 2 publications

(2 citation statements)

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“…At this thickness, various surface and interface effects become more pronounced. Energy level compatibility at the organic compound-organic compound (OC-OC) and the electrode-organic compound interface can greatly influence the performance of the devices such as organic light emitting diodes (OLEDs) [6,7] and organic photovoltaic (OPV) cells [8][9][10]. At small film thickness, the ionization energy and electron affinity level shift can be observed due to the Fermi level alignment between two different materials [11,12].…”

Section: Introductionmentioning

confidence: 99%

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

Gržibovskis

Vembris

2018

J Mater Sci

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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 bulk heterojunction system studies. 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 sample morphology on the PYS measurements and obtainable results, phase separated and homogeneously distributed samples were prepared for analyses. P3HT ionization energy shift of 0.40eV 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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Section: Introductionmentioning

confidence: 99%

“…Few attempts have been made to investigate the molecule ionization energy in the bulk heterojunction samples obtained from the solution by the UPS method [21,22]. Tsoi et al [22] have investigated pure poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) films and their blends.…”

Section: Introductionmentioning

confidence: 99%