Commercially available silicon diodes are suitable as temperature sensors over a wide range of temperature. Despite their robustness, abundance and very low cost, they are seldom used in high school or junior undergraduate laboratories as temperature sensors. Here we describe a simple circuit based on an inexpensive quad operational amplifier that permits a direct reading temperature instrument to be constructed using silicon diodes, thereby encouraging their use in introductory thermal experiments.

The spatial distribution of ubiquitous green luminescence (GL) in ZnO nanorods is investigated using cathodoluminescence (CL) spectral imaging. The vertically aligned, single‐crystal nanorods exhibit a strong GL emission at 2.42 eV at 80 K, attributable to oxygen vacancies. The spectral imaging reveals the GL emission is predominantly located in the surface layer of nanorods; the thickness and intensity of this layer decreases rapidly at elevated temperatures. On the other hand, the near‐band‐edge emission is weakest near the nanorod edges. The temperature‐dependent CL maps are consistent with the properties of a model in which singly ionized oxygen vacancies are stabilized by the surface band bending, which leads to the GL enhancement at the expense of near‐band‐edge emission. These results demonstrate the utility of spectral CL imaging to map the spatial distribution of defect luminescence in nanostructured materials.

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Organolead mixed-halide perovskites capable of emitting multiple colors not only allow the fabrication of compact devices but also improves the functionality of light emitting devices beyond conventional displays. Here we demonstrate a costeffective chemical dip-coating technique to grow highly reproducible methylammonium-lead-halide perovskite film, which exhibits highly efficient multi-color emissions of red, green and ultraviolet. The power-and temperature-resolved cathodoluminescence analyses reveal that these emissions are attributed to localized excitions with thermal activation energies of 27, 29 and 57 meV. The non-linear fitting of these emission band widths within the frame work of Boson model reveals that excitons are strongly coupled to the lattice with energy of 28 meV, which is consistent with the Raman measurement. This work presents an effective method for the deposition of high-quality and large-area perovskite film, which could be useful for high-performance multi-color display devices.[a] A.