Photovoltaic devices from CdSe nanocrystals and conjugated polymer composites

Abstract

The preparation of CdSe nanospheres (ns-CdSe) and their application as electron acceptor in conjugated polymer photovoltaic devices are reported. ns-CdSe with diameters of 5 nm were prepared through an organometallic method. The transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis) absorption and photoluminescence (PL) spectra indicate that the CdSe nanocrystals (NCs) are monodispersed nanospheres with the first exciton absorption peak at around 625 nm and the emission peak at around 652 nm. The PL spectra of the ns-CdSe/polymer composite films show that the PL of the conjugated polymers is effectively quenched upon the addition of ns-CdSe. Photovoltaic devices were fabricated from the composites of ns-CdSe and poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) or poly(3-hexylthiophene) (P3HT). Under AM1.5 illumination (100 mW/cm²), the short circuit current (I_SC), open circuit voltage (V_OC), fill factor (FF) and energy conversion efficiency (η) reached 1.56 mA/cm², 0.75 V, 34.5% and 0.40%, respectively for device from the ns-CdSe/MEH-PPV (15 : 1 by weight) and 1.93 mA/cm², 0.65 V, 38.4% and 0.48%, respectively for device from the ns-CdSe/P3HT (10 : 1 by weight).

Keywords

CdSe nanocrystals, conjugated polymer, photovoltaic devices