Enhancement of Power Efficiency and Stability of P3HT‐Based Organic Solar Cells under Elevated Operating‐Temperatures by Using a Nanocomposite Photoactive Layer

With the aim to find out an enhanced operating‐temperature range for photovoltaic device parameters, two types of the photoactive layer were prepared: poly(3‐hexylthiophene) (P3HT) and P3HT+nc‐TiO 2 (PTC) thin films. The enhancement obtained for the photoelectrical conversion efficiency of the composite based OSCs is attributed to the presence of nanoheterojunctions of TiO 2 /P3HT. For the temperature range of 30–70°C, the decrease of the open‐circuit potential was compensated by an increase of the fill factor; and the increase in the short‐circuit current resulted in an overall increase of the energy conversion efficiency. At elevated temperatures of 60–80°C the efficiency of the P3HT‐ and PTC‐based cells reached a maximum value of 1.6% and 2.1%, respectively. Over this temperature range the efficiency of P3HT‐based OSC decreased strongly to zero, whereas for the PTC cells it maintained a value as large as 1.2% at the temperature range of 110–140°C. The improved thermal stability of the composite‐based device was attributed to the lowered thermal expansion coefficient of the nanocomposite photoactive layer.