Infrared solar cells that utilize low-bandgap colloidal quantum dots (QDs) are promising devices to enhance the utilization of solar energy by expanding the harvested photons of common photovoltaics into the infrared region. However, the present technology for synthesis of PbS QDs cannot produce highly efficient infrared solar cells. Here, we develop a general synthesis framework for low-bandgap PbS QDs (0.65-1 eV) via cation-exchange from ZnS nanorods (NRs). First, ZnS NRs are converted to superlattices with segregated PbS domains within each rod. Then, sulfur precursors are released via dissolution of the ZnS NRs during the cation-exchange, which promotes size-focusing of PbS QDs. PbS QDs synthesized through this new method have the advantages of high monodispersity, ease of size control, in-situ passivation of chloride, high stability, and "clean" surface. We fabricated infrared solar cells based on these PbS QDs with different bandgaps, using conventional ligand exchange and device structure. All of our devices produced in this manner show excellent performance, showcasing the high quality of our PbS QDs. The highest performance of infrared solar cells was achieved using ~0.95 eV PbS QDs, exhibiting an efficiency of 10.0% under AM 1.5 solar illumination, a perovskitefiltered efficiency of 4.2% and a silicon-filtered efficiency of 1.1%.

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This paper proposes a look-up table based maximum torque control of interior permanent magnet synchronous motor (IPMSM) for traction of electric vehicles (EV). Maximum torque control is preferable for traction requirement of EV due to requirements of high torque ability in lower speed and wideadjustable operation range. In constant torque region (below rating speed), Maximum Torque per Ampere (MTPA) can achieve perfect performance, while in field-weaking region (over rating speed), the torque control usually is not satisfactory. The main problem is that on-line calculation of current commands is too complex and time-consuming in real control system. We solved the problem through construction of look-up table for d-axis current off-line, and on-line calculation of q-axis current using torque equation. It can not only permit the maximum torque control performance but also easy for micro-controller to implement. Finally, simulation and experimental system were constructed to verify the proposed method, and results have been found in good agreement with theoretic analysis.

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