Solution Synthesis Of ?In,Ga?₂Se₃ Nanocrystals And Its Application For Phase Formation Of Chalcopyrite Cu?In,Ga?Se₂

?₂-?₃ compounds,In₂Se₃,Ga₂Se₃ and?In,Ga?₂Se₃,have different phase structures.They can be applied in various fields due to their unique electrical and optical properties,such as phase change random access memories?PRAM?and visible light sensors.Moreover,In₂Se₃,Ga₂Se₃ and IGSe films have been commonly employed as precursor layers for preparation of chalcopyrite CuInSe₂,CuGaSe₂ and Cu(In_1-xGa_x)Se₂?CIGSe?.CIGSe has excellent physical properties,such as high quantum efficiency,tunable band-gap energy,long-term excitation stability,which has been known as excellent light-absorbing materials for high-efficiency?beyond 20%?thin film solar cells.In this paper,(In_1-xGa_x)₂Se₃ nanocrystals?0?x?1?were synthesized by a facile,air pressure ethylenediamine/N-dodecyl mercaptan co-assisted triethylene glycol solution process using InCl3·4H2O,GaCl3 and Se powder as precursors.Such a technique may lead to cheap fabrication cost,less environmental pollution and material loss.The synthesized products deposited on clean glass substrates by dip-coating method were annealed at 500? for 1 hour.In order to optimize the processing parameters in the synthesis of(In_0.7,Ga_0.3)₂Se₃,the amounts of EN and NDM as well as injection/reflux temperature were investigated by SEM,TEM,XRD,EDS,UV-Vis-NIR,Raman and Hall measurement.In addition,morphologies of the synthesized(In_1-xGa_x)₂Se₃ nanocrystals?0?x?1?were observed.Controllable solid solution stoichiometries,phase composition,tunable band gap energies and Hall parameters with chemical stoichiometries of the prepared?In1-x,Gax?₂Se₃ products with solid solution range of 0?x?1 were discussed.At last,Cu?In,Ga?Se₂ thin films were prepared by dip-coating method using both?In,Ga?₂Se₃ nanocrystal ink and CuS thin film or Cu²⁺ solutions.The research results showed that(In_0.7,Ga_0.3)₂Se₃ nanocrystal products with perfect In/Ga ratio,well dispersion,near-granular shape particle with 50nm size were prepared by hot-injection method using[Se]:[In]:[Ga]= 1.5:0.7:0.3 in precursor solutions,1mL ethylenediamine?EN?and 0.075mL N-dodecyl mercaptan?NDM?as reactive assistants in 40 mL anionic precursor solutions,injecting 10 mL cationic precursor solutions at 230? and refluxing reaction solution at 210? for 30 min.Moreover,(In_1-xGa_x)₂Se₃ nanocrystals?0?x?1?with controllable chemical stoichiometries and near-granular shape were synthesized with different In/Ga ratios in precursor solutions.The In/Ga atomic ratios of the synthesized nanocrystals could be matched well with those of the feeding solutions.The annealed(In_1-xGa_x)₂Se₃ had hexagonal defect wurtzite structure,n-conductivity and tunable band gap energies of 1.88eV-2.01eV in the range of 0?x?0.3,and had cubic defect zinc-blende structure,p-conductivity and tunable band gap energies of 1.76eV-2.10eV in the range of 0.5?x?1.0.(In_1-xGa_x)₂Se₃ nanocrystals showed a mixed phase of wurtzite and zinc-blende structure at x = 0.4 and 0.45,respectively.Cu(In_0.7Ga_0.3)₂Se₃ thin films with chalcopyrite structure could be prepared by lamination of(In_0.7,Ga_0.3)₂Se₃ nanocrystal layers and Cu²⁺ solutions or CuS thin films.