Template-free synthesis of vertically aligned CdS nanorods and its application in hybrid solar cells

We have fabricated and investigated hybrid solar cells based on one-step fabricated vertically aligned CdS nanorod arrays and poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV). The vertically aligned CdS nanorods provide the minimal electron transport path to reduce the charge carrier recombination at the heterojunction interface. The photoactive layers were prepared by two deposition methods, dip- and spin-coating of MEH-PPV on CdS nanorods. Scanning electron microscope (SEM) showed that the extent of infiltration of the soft MEH-PPV phase into the rigid CdS nanorods arrays can be controlled by different deposition methods, which strongly influence the PV device performance. The influence of annealing treatment on the device performance is also studied; the power conversion efficiency is quadrupled for dip-coating and doubled for spin-coating after the annealing treatment.