Aqueous-solution-processed PPV–CdxHg1−xTe hybrid solar cells with a significant near-infrared contribution

Abstract

Aqueous poly(p-phenylene-vinylene) (PPV):Cd_xHg_1−xTe nanocrystal (NC) hybrid solar cells are prepared with heat-introduced aggregation and growth of the NCs. The morphology of the active layer is easily controlled by tuning the composition of the donor and acceptor and the charge carrier mobility is largely improved after annealing for 1 h. Through passivating the surface traps on the NCs with the UV-ozone radiation, the V_oc can be improved. The photovoltaic devices present a wide response range in the solar spectrum from UV to 1200 nm. The near-infrared absorption is attributed to the Cd_xHg_1−xTe NCs and the absorption extends to near-infrared as the Cd/Hg ratios decrease, which favors the stability of the NCs due to the strong ionic bond of HgTe. The power conversion efficiency (PCE) of such photovoltaic devices exhibits about 1.5% under AM 1.5G illumination with a high short-circuit current density (J_sc) of 12.84 mA cm⁻². 11.4% near-infrared contribution is observed from the external quantum efficiency (EQE) measurement with only simple device structures.