Efficient hybrid solar cells using PbSxSe1−xquantum dots and nanorods for broad-range photon absorption and well-assembled charge transfer networks

Abstract

We present hybrid solar cells with high efficiency utilizing a novel donor–acceptor combination of poly[2,6-(4,4′-bis-(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-alt-4,7(2,1,3-benzothiadiazole)] (PSBTBT) and a PbS_xSe_1−x inorganic semiconductor. Several nanocomposite parameters are evaluated in order to improve the hybrid device efficiency, including donor–acceptor materials, surface modification of the inorganic semiconductor, and mixture of quantum dots (QDs) and nanorods (NRs) in the polymer matrix. A high power conversion efficiency (PCE) of ∼3.4% is attained from the optimal device with a PbS_0.7Se_0.3 QD : NR blending ratio of 0.3 : 0.7 (wt/wt) under air mass (AM) 1.5 solar illumination, which is attributed to the broad-range absorption of the solar energies and the efficient charge separation and transport dynamics. The optoelectronic and nanomorphological properties of these novel hybrid solar cells are described.