Fluorinated- and non-fluorinated-diarylamine-Zn(ii) and Cu(ii) phthalocyanines as symmetrical vs. asymmetrical hole selective materials

Abstract

Four symmetrically substituted and four asymmetrically substituted fluorinated and non-fluorinated-diarylamine CuPcs and ZnPcs have been designed and utilized as hole transporting materials in perovskite solar cells in a planar n–i–p structure. We established the correlation between the electronic structure, charge mobility parameters, core metal, and substituents in metal phthalocyanines. The fluorinated asymmetrically substituted undoped ZnPc-6 yielded the best power conversion efficiency of 15.40% with an open-circuit voltage (V_oc) of 1016.1 mV, a short-circuit current density (J_sc) of 21.27 mA cm⁻², and a fill factor (FF) of 71.25%, followed by the non-fluorinated asymmetrically substituted ZnPc-5 with 14.36%. In the case of symmetrical CuPcs, the best performance was measured using non-fluorinated CuPc-3 and fluorinated CuPc-4 gave 11.53% and 10.90% of PCEs, respectively. Importantly, the devices with MPcs showed improved stability under multi-stress conditions.