Charge transport and prototypical optical absorptions in functionalized zinc phthalocyanine compounds: A density functional study. (8th November 2017)

• Record Type: Journal Article
• Authors: Sahoo, Smruti Ranjan; Sahu, Sridhar; Sharma, Sagar
• Is Part Of: Journal of physical organic chemistry. Volume 31:Number 4(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-11-08
• Subjects: charge transport -- density functional theory -- functionalization -- optical absorption -- zinc phthalocyanines; Chemistry, Physical organic -- Periodicals; 547.1
• DOI: 10.1002/poc.3785
• Languages: English
• ISSNs: 0894-3230

Abstract

Abstract: Metal phthalocyanines are considered to be prominent candidates for designing organic semiconductors. However, enhancing n‐type characteristics and air stability in these compounds have been the major challenges. Earlier studies on zinc phthalocyanines (ZnPc) reported enhancement in electron mobility due to fluorination. We present a theoretical study of the charge transfer and optical properties of functionalized zinc phthalocyanines (XZnPc, with X = F16, Cl16, Br16, I8, and (CN)8 ) within the framework of the density functional theory. Substitutions with electron‐withdrawing groups at the peripheral sites of ZnPc was found to lower both EHOMO and ELUMO in the compounds. Computed values of electron affinity (EA) > 3 eV in all XZnPcs indicated effective electron injection inferring enhanced n‐type characteristics and air stability in these compounds. However, cyanation ((CN)8 ), as compared to the other EWGs, is found to enhance the electron mobility more prominently in the compound. In addition, studied optical absorption spectra of all XZnPc compounds at different exchange‐correlation functionals such as B3LYP, PBE0, CAM‐B3LYP, wB97xD, M06, and M06‐2X exhibited Q‐band in visible region (∼600‐700 nm) and B‐band (Soret) in ultraviolet (∼300‐400 nm) region, and a few shows an N‐band below 300 nm. Upon functionalization, the B‐band and Q‐band maxima show bathochromic shift both in gas phase and dimethyl sulfoxide. All these optical absorptions were found to be prototypical in nature, and the spectra are assigned to π → π ∗ character. Abstract : A DFT study of the effect of functionalization on the charge transfer and optical absorption of ZnPc is presented. Functionalization of ZnPc is found to lower its energy levels and also the energy barrier leading to enhance n‐type characteristics and air stability in the compounds. Optical absorption in all functionalized ZnPc is prototypical in nature and exhibits Q‐band, Soret band (B), and N‐band, and leads to red shift in the absorption spectra.