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Organic emissive materials equipped with tuneable optical properties have gained serious attention. Herein, two phenanthroline derivatives (ImPhTz and ImPhOz) have been prepared to possess an imidazole-thiadiazole/oxadiazole core and their tuneable emission behaviors have been investigated. As a result, ImPhTz is described with emission wavelengths spanning the visible region (λem = 481–611 nm) with different excitation wavelengths. The absorption (359 nm) and emission (478 nm) wavelengths of ImPhTz were red-shifted 52 nm and 93 nm when the pH value increased from 1.70 to 13.29, respectively. It is worth noting that the fluorescence quantum yields of ImPhTz did not reduce with the increase in pH values. Thus, multicolor photoluminescence has been achieved based on a single organic chromophore. Comparatively, ImPhOz was less sensitive to environmental stimulus due to a lower degree of conjugation. The emission wavelength of ImPhOz is red-shifted 82 nm and 69 nm when the excitation wavelengths and pH values increased, respectively. Moreover, the maximum two photon absorption cross-section value of ImPhTz (190 GM) is also higher than ImPhOz (27 GM). In other words, the optical properties of molecules equipped with thiadiazole may be more sensitive to the environment than those equipped with oxadiazole.

Semiconducting bismuth sulfide (Bi2S3) nanoplates with unique highly oriented {001} surfaces were prepared on a large scale using a novel organic precursor Bi(DTCA)3 (DTCA = carbazole-9-carbodithioic acid). The as-prepared Bi2S3 nanoplates were dispersed in dimethyl sulfoxide (DMSO) and spin-coated onto an indium tin oxide (ITO) coated glass substrate. With a simple ITO/Bi2S3/Al stacked structure, the fabricated sandwich-like memory device demonstrates dynamic random access memory (DRAM) characteristics with a maximum ON/OFF current ratio up to 10(6) and a long retention time. It is suggested that the volatile nature of the memory device comes from the Schottky contact between the Bi2S3 nanoplates and the Al electrodes.