Electrochemical and photovoltaic properties of highly efficient solar cells with cobalt/zinc phthalocyanine sensitizers

The cyclic voltammetry studies indicated that the HOMO and LUMO energy levels of three sensitized metallophthalocyanines could ensure efficient electron injection and thermodynamically favorable dye regeneration. The S-bridged 4-mercaptobenzoic acid substituted cobalt(II) phthalocyanine (4-MKBa-CoPc) sensitized solar cell devices possessed a short-circuit photocurrent density of 9.70 mA/cm², an open-circuit voltage of 0.88 V, and a fill factor of 0.49, corresponding to an overall conversion efficiency of 4.18% under standard AM 1.5 sun light. The present results demonstrated that the cobalt(II) phthalocyanine derivative had dramatically higher solar cell efficiency value as compared to zinc(II) phthalocyanine and as a linker atom, instead of oxygen linker, sulfur atoms slightly improved solar cell efficiency. The above results indicated that a low cost sensitizer made up of symmetrically substituted phthalocyanine with an earth abundant metal at the inner core can reach sufficiently high solar cell efficiency when compared with the alternative sensitizers for DSSCs applications.