can the element you mentioned before be used in electronics?
Yes, it is used in photoresistors.
Thallium
Thallium(I) sulfide's electrical conductivity changes with exposure to infrared light therefore making this compound useful in photoresistors. 
what is thallium? A chemical element. what are its characteristics? A thallium atom has 81 electrons arranged in the configuration [Xe]4f5d6s6p. It is malleable and sectile enough o be cut with a knife at room temperature. It has a metallic luster. how many isotopes does it have? 41. how is it produced? It is obtained as a by-product of smelting of copper, zinc, and lead ores. is it used in medicines? It is used for stress tests for risk stratification in patients with coronary artery disease. what are the symptoms of the disease that you just mentioned? Angina, shortness of breath, sweating , nausea or vomiting and lightheadedness.
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Thallium [SEP] Electronics
Thallium(I) sulfide's electrical conductivity changes with exposure to infrared light therefore making this compound useful in photoresistors. Thallium selenide has been used in a bolometer for infrared detection. Doping selenium semiconductors with thallium improves their performance, thus it is used in trace amounts in selenium rectifiers. Another application of thallium doping is the sodium iodide crystals in gamma radiation detection devices. In these, the sodium iodide crystals are doped with a small amount of thallium to improve their efficiency as scintillation generators. Some of the electrodes in dissolved oxygen analyzers contain thallium.