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

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 PbSxSe1-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 PbS0.7Se0.3 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.