Investigation of aluminum phthalocyanine chloride as acceptor material in planar organic solar cells: comparative study with fullerene

Aluminum Phthalocyanine Chloride (AlPcCl) is generally known as donor material in organic photovoltaic cells (OPVs). Nevertheless, in the present study we have demonstrated a successful use of AlPcCl as acceptor material to replace fullerene (C 60 ) in a planar heterojunction OPVs based Alpha-Sexithiophene (α-6T) as donor material. For this purpose, we have elaborated two series of OPVs: α-6T/AlPcCl and α-6T/C 60 using thermal sublimation technique. After the optimization of the AlPcCl thickness we have compared both solar cells current density vs. voltage characteristics, we have shown that the use of AlPcCl as acceptor instead of C 60 induces to an increase in the open circuit voltage (V oc ) and the short current density (J sc ) values by 18% and 23%, respectively, from 0.5 to 0.61 V and from 6.10 to 7.98 mA/cm 2 , while, we have obtained a decrease in the shunt resistance which has dropped the fill factor (FF) from 58 to 51%. The V oc and J sc increase allows to increase the power conversion efficiency by 28%. These findings have been supported by absorbance measurements and morphological studies. The V oc and J sc increase have been discussed and assigned to the difference between the theoretical V oc of both heterojunctions, and to the complimentary absorption of AlPcCl with α-6T. While, the FF deceases has been attributed to the low electron mobility of AlPcCl compared with C 60 . These findings, brought in the spotlight the potential of the metal phthalocyanines, which can open up a wide range of possibilities to test other materials based like this family.