Abstract
The effects of the substituent in p-substituent-benzylidenemalononitrile small molecules have been investigated. We found that the replacement of cyano group in the molecule (M1) by a nitro group (M2) reduces the optical and the electrochemical band gap value which is correlated with a red shift in the absorption and photoluminescence spectra. The insertion of both molecules in P3HT and PCDTBT polymers showed that the quenching parameter efficiency increase from 42 to 71% and from 51 to 64%, respectively. We conclude that M2 is an efficient quencher in P3HT. Electrical measurements in dark showed a diode behaviour for all devices. The effective hole mobility
μ
eff
was calculated and shows an enhancement in the case of ITO/P3HT:M2/Al. The calculated values are comparable to those in the literature.