Performance enhancement of fullerene based solar cells upon NIR laser irradiation

Photovoltaic performance enhancement of fullerene based solar cells was achieved upon exposure to near-infrared (NIR) laser pulses. The solar cells were fabricated with poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) under ambient conditions. The cells were then post-treated with NIR femto-second laser pulses at 800 nm for different intervals of time. An enhancement of 50% in the power conversion efficiency was achieved for the devices with 15 minutes of NIR laser irradiation compared to that of the control device. The enhancement in the power conversion efficiency is attributed to the formation of a covalent linkage between P3HT and PCBM as suggested by Matrix-assisted laser desorption/ionization time of flight mass spectroscopic analysis on a blend of a thiophene oligomer and PCBM before and after NIR laser exposure.