Low molecular mass organic compounds which make thin films from volatile organic solutions would be great benefit in future
organic light emitting systems. Two most important advantages could be mentioned. First - the repetition of synthesis of small
molecules is better than for polymers. Second - wet casting methods could be used.
In this work we are presenting optical, electroluminescence and amplified spontaneous emission properties of four original glassy
forming compounds containing 2-tert-butyl-6-methyl-4H-pyran-4-ylidene fragment as backbone of the molecule. They has the same
N,N-dialkylamino electron donating group with incorporated bulky trityloxy ethyl groups. The difference of these compounds is in
electron acceptor group. One has 1H-indene-1,3(2H)-dione group, second has pyrimidine-2,4,6(1H,3H,5H)-trione group, third has
malononitrile group and fourth has 2-ethyl-2-cyanoacetate.
Absorption maximum of the compounds is between 420 and 500 nm and is red shifted from weaker acceptor group to stronger one.
The electroluminescence efficiency for simple device ITO/PEDOT:PSS/Organic compound/BaF/Al is low. For the best one with
malononitrile group it was 0.13 cd/A and 0.036 lm/W. It could be increased by optimising the sample geometry or adding addition
layers for charge carrier transport and exciton blocking. But nevertheless the use of these compounds in organic light emitting devices
in neat films is unlikely.
Attached bulky trityloxy ethyl groups and tert-butyl group decrease interaction between the molecules thus allowing to obtain
amplified spontaneous emission in neat thin films for all investigated compounds.