On exploring electrochemical, electrical and optoelectronic properties of B 25 C 2

In this work, the electrochemical, electrical and optoelectronic properties of a recently synthesised vacancy-containing low-density superhard boron carbide (B25C2 as per stoichiometry) have been investigated. Although quite a significant value of specific capacitance is obtained only at low scan rates (for cyclic voltammetry studies) or at low applied current (for galvanostatic charge–discharge test), a declining trend of specific capacitance is observed with increasing scan rate or applied current. Such a pseudocapacitive behaviour, as a consequence of restricted diffusion through available defects (vacancies), would be applicable in situations requiring slow, steady energy release where the entire material matrix has time to interact with the electrolyte. Furthermore, UV-visible spectroscopy and photoluminescence results identify this material as a wide direct band gap semiconductor with a band gap of 3.07 eV that corresponds to an optical absorption/emission edge in the near-ultraviolet spectrum (≈404 nm), right at the boundary of visible violet light; thereby elucidating significant optoelectronic applications. Finally, the Schottky diode characteristic, exploring a combination of an ideality factor of 1.08, barrier height of 0.67 V and series resistance of 3.1 kΩ, indicates a device that is nearly ideal in its carrier transport but limited by high internal resistance; thereby making it suitable for specific low-current signal applications.