Although CrSi 2 silicide is an attractive advanced functional material, the improvement of electronic and optical properties is still a challenge for its applications. Here, we apply the first-principles calculations to investigate the influence of transition metals (TMs) on the electronic and optical properties of C40 CrSi 2 silicide. Five possible TMs, Ti, V, Pd, Ag, and Pt, are considered in detail. The calculated results show that the additive metals Ti, V, Pd, and Pt are thermodynamically stable in C40 CrSi 2 because the calculated impurity formation energy of TM-doped C40 CrSi 2 is lower than zero. In particular, the V dopant is more thermodynamically stable than that of the other TMs. The calculated electronic structure shows that the band gap of C40 CrSi 2 is 0.391 eV, which is in good agreement with the other results. In particular, the additive TMs improve the electronic properties of C40 CrSi 2 due to the role of the d-state of TMs. Naturally, the additive TMs result in band migration (Cr-3d state and Si-3p state) from the valence band to the conduction band. Interestingly, the additive TMs lead to a red shift for optical adsorption of C40 CrSi 2 silicide. K E Y W O R D S alloying, C40 CrSi 2 , electronic properties, first-principles calculations, optical properties 1 | INTRODUCTION Transition metal (TM) silicides are attractive advanced functional materials due to their excellent electronic properties, good thermoelectric properties, high temperature strength, excellent oxidation resistance, etc. [1-13] For example, the previous works have shown that tungsten silicides are regarded as fascinating renewed thermoelectric or energy materials. [14-17] Molybdenum (Mo) or niobium (Nb) silicides are attractive hightemperature structural materials due to their high melting point, greater hardness, good thermodynamic stability, etc. [18-24] Recently, chromium silicide (CrSi 2) has received great attention as thermoelectric and storage energy materials. [25-27] It is well known that the overall performances of TM silicides or compounds are markedly influenced by their structural feature. [28-32] Regarding thermoelectric materials, Zhang and Wang have found that the higher anisotropy of electrical conductivity results in the thermoelectric properties of the hexagonal CrSi 2 , [33] while the narrow band gap of C40 CrSi 2 is 0.3 to 0.35 eV. Oader and Venkat prepared a CrSi 2 thermoelectric thin film using the magnetron sputtering method. [34] Furthermore, Mikami and Kinemuchi studied the microstructure and thermoelectric performance of WSi 2 on CrSi 2 silicide. [35] They found that the additive WSi 2 reduces the grain size of CrSi 2 and improves the ZT value of CrSi 2-based material. Regarding promising storage energy material, Menda and Ozdemir studied the capacitance voltage temperature (C-V-T) and current voltage temperature (I-V-T) of p-CrSi 2 /Si using the physical vapor deposition (CAPVD) method, [36] while the measured building voltage was about 0.7 V. Bhamu and Ahuja theoretically studied the electronic st...