Hybrid nanocrystal/polymer solar cells based on tetrapod-shaped CdSe _xTe_1-x nanocrystals

A series of ternary tetrapodal nanocrystals of CdSe_xTe _1-x with x ≤ 0(CdTe), 0.23, 0.53, 0.78, 1 (CdSe) were synthesized and used to fabricate hybrid nanocrystal/polymer solar cells. Herein, the nanocrystals acted as electron acceptors, and poly(2-methoxy-5-(2′-ethyl- hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) was used as an electron donor. It was found that the open circuit voltage (V_oc), short-circuit current (J_sc) and power conversion efficiency (η) of the devices all increased with increasing Se content in the CdSe_xTe_1-x nanocrystals under identical experimental conditions. The solar cell based on the blend of tetrapodal CdSe nanocrystals and MEH-PPV (9:1w/w) showed the highest power conversion efficiency of 1.13% under AM 1.5, 80mWcm^-2, and the maximum incident photon to converted current efficiency (IPCE) of the device reached 47% at 510nm. The influence of nanocrystal composition on the photovoltaic properties of the hybrid solar cells was explained by the difference of the band level positions between MEH-PPV and the nanocrystals.