The dye-sensitized solar cells based on the functionalized organic sensitizer, 3-(5-(5-(4-(bis(4-(hexyloxy)-phenyl)amino)phenyl)thiophen-2-yl)thiophen-2-yl)-2-cyanoacrylic acid (D21L6) exhibit comparable stability to the ruthenium sensitizers under 60 degrees C heat stress and AM 1.5 light illumination where the overall efficiency remained at above 90% of the initial value after 1000 h. However, at 80 degrees C heat stress without light soaking the overall efficiency of dye-sensitized solar cell remained at 80% of the initial value after 1000 h. The main reason for loss of performance was a decrease in open circuit photovoltage (V-oc) under light soaking conditions and in photocurrent (J(sc)) under heat stress, respectively. In this regard, interfacial charge carrier recombination and change of capacitance due to aging under light soaking or heat stress were studied. (C) 2010 Elsevier Ltd. All rights reserved.