Synthesis, Characterization and Photo Response Behaviour of InSe and CuInSe₂ Nanostructures Using Tris(5‐methyl‐2‐pyridylselenolato)indium(III) as Molecular Precursor

Abstract

This report presents the synthesis of organoselenium compound {SeC5H3(Me‐5)N}2 (1) and corresponding derivative of In(III), [In{SeC5H3(Me‐5)N}3] (2) and their characterization by elemental analysis, heteronuclear NMR (1H, 13C, 77Se) spectroscopy and single crystal X‐ray diffraction. The utilization of In(III) complex as molecular precursor has been demonstrated for the preparation of rare cubic phase of InSe. The complex has also been used for the preparation of tetragonal CuInSe2. The crystal structure, phase purity, morphology and elemental composition of these nanostructures were evaluated by powder X‐ray diffraction and electron microscopic techniques. The effect of increase in temperature is manifested in the increase of particle size of InSe and morphological variation from sheet to polygon in case of CuInSe2. The optical band gap of the nanostructures as deduced from diffuse reflectance spectroscopy (DRS) found to be in the range 1.84‐1.75 eV for InSe and 1.99‐1.78 eV for CuInSe2 which are optimum for solar energy harvesting. The band gap values are blue shifted relative to their respective bulk counterparts indicating quantum confinement effect in the nanostructures. Both InSe and CuInSe2 nanostructures showed photo response with faster switching characteristics which makes them promising candidate for alternative low cost photon absorber material.

Synthesis of photo-responsive indium selenides (InSe and In2Se3) from tris(4,6-dimethyl-2-pyrimidylselenolato)indium(iii) as a molecular precursor

“…This observation is quite interesting in terms of the fact that most of the similar types of chelated tris indium complexes containing heteronuclear selenolate ligand (pyridyl/pyrimidyl) crystallize to give fac (facial) isomers. 17,21,27 Only one meridional isomer of such a complex has been reported so far for tris(8-selenanylquinolinato)indium( ii )tetrahydrate by Pech et al 28 Moreover, in the present case, only two In–Se (2.55 and 2.57 Å) and In–N (2.44 and 2.38 Å) distances are in agreement with those reported for similar types of complexes such as [In(SeC 5 H 4 N) 3 ], In[SeC 5 H 3 (3-SiMe 3 )N] 3 , In[SeC 5 H 3 (Me-3)N] 3 and In[SeC 5 H 3 (Me-5)N] 3 . 17,21 The third pyrimidylselenolate moiety chelates to the central In atom with In–Se and In–N distances of 2.6115(6) and 2.731 Å, respectively, which are noticeably longer than the average In–Se and In–N distances for isostructural In complexes.…”

“…17,21,27 Only one meridional isomer of such a complex has been reported so far for tris(8-selenanylquinolinato)indium( ii )tetrahydrate by Pech et al 28 Moreover, in the present case, only two In–Se (2.55 and 2.57 Å) and In–N (2.44 and 2.38 Å) distances are in agreement with those reported for similar types of complexes such as [In(SeC 5 H 4 N) 3 ], In[SeC 5 H 3 (3-SiMe 3 )N] 3 , In[SeC 5 H 3 (Me-3)N] 3 and In[SeC 5 H 3 (Me-5)N] 3 . 17,21 The third pyrimidylselenolate moiety chelates to the central In atom with In–Se and In–N distances of 2.6115(6) and 2.731 Å, respectively, which are noticeably longer than the average In–Se and In–N distances for isostructural In complexes. This behaviour of the third selenolate ligand arises from the steric effect rendered in the molecule by methyl group hydrogens attached to C17 and C5, which are in close proximity.…”

“…The steric effect amongst the ligands can be further realized from the disparity between the Se–In–Se bond angles. While two of the bond angles 108.57(2) and 110.95(2)° for Se(2)–In(1)–Se(3) and Se(1)–In(1)–Se(3), respectively, fall in line with those reported for [In(SeC 5 H 4 N) 3 ], In[SeC 5 H 3 (Me-3)N] 3 and In[SeC 5 H 3 (Me-5)N] 3 , 17,21 the third bond angle of 136.94(3)° for Se(1)–In(1)–Se(2) is considerably larger than the same for the aforementioned complexes. The average Se–In–N bond angle (66.12°) is also comparable with those reported for similar complexes cited earlier in this section.…”

“…Previously, our group has successfully demonstrated the utility of a 5-methyl-2-pyridylselenolate complex of In( iii ) for the preparation of the rare cubic phase of InSe. 21 However, producing phase pure and highly photoresponsive In 2 Se 3 and InSe from the same SSP is a dream not yet realized.…”

Synthesis and structure of [(Ph3P)2Cu(μ-SeCH2Ph)2In(SeCH2Ph)2] as a single-source precursor for the preparation of CuInSe2 nano-materials

“…S15, ESI †) and matches well with the reported values. 27 The direct band gaps of CuInSe 2 nanostructures showed a blue shi compared to the bulk CuInSe 2 i.e. 1.04 eV.…”