Alkyl chain length dependence of carrier transport in solution-processed phthalocyanine thin films evaluated via MIS-CELIV method

Abstract

Abstract The carrier transport characteristics of 1,4,8,11,15,18,22,25-octaalkylphthalocyanine (CnPcH2) thin films have been investigated by utilizing metal–insulator–semiconductor charge extraction by the linearly increasing voltage method. As the alkyl chain length of CnPcH2 increased from n = 5 to 8, the estimated hole mobility decreased by almost one and a half order of magnitude in the range of 10−4 to 10−5 cm2 V−1 s−1. Furthermore, the relationship between the alkyl chain length and site energy distribution in solution-processed phthalocyanine thin films was investigated. The temperature and field dependences of the hole mobility were analyzed using the Gaussian disorder model, and the effect of the alkyl chain length was discussed by taking the enlargement of the energetic width of the hopping site and the distribution of the hopping distance into consideration.