02311nas a2200265 4500008004100000245012900041210006900170260000800239300001600247490000700263520139200270100001601662700002001678700002101698700001801719700002101737700002401758700002001782700002401802700002601826700002401852700001901876700002001895856013001915 2018 eng d00aHydrothermal synthesis of rGO-PbBi2Se4 composite and investigation of its structural, chemical and field emission properties0 aHydrothermal synthesis of rGOPbBi2Se4 composite and investigatio cJUN a10494-105030 v293 aIn the present study we report the one step facile synthesis of pristine lead bismuth selenide (PbBi2Se4) and reduced graphene oxide (rGO) and its composites with PbBi2Se4. Formation of pristine PbBi2Se4 and rGO-PbBi2Se4 composite were confirmed by X-ray diffraction and X-ray photoelectron spectroscopy. The surface morphology and topography investigated by using scanning electron microscopy and transmission electron microscopy revealed the formation of nano-flowers pristine PbBi2Se4. After coupling pristine PbBi2Se4 with rGO the surface morphology shows the formation of sharp vertically protruded nano-sheets/nano-flaks originated from the nano-flowers. Finally, the field emission properties of pristine PbBi2Se4 and rGO-PbBi2Se4 composite have been investigated. It has been observed that the rGO-PbBi2Se4 composite emitter exhibited excellent field emission properties with low turn-on field (similar to 2.8 V/A mu m for 10 A mu A/cm(2)), high emission current density (similar to 1288 A mu A/cm(2) at 3.9 V/A mu m) and superior current stability (similar to 4.5 h for similar to 1 A mu A) compare to pristine PbBi2Se4 emitter. Thus, the facile one step synthesis approach and robust nature of rGO-PbBi2Se4 composite emitter can provide prospects for the future development of large-area emitter applications such as flat-panel-display and vacuum micro/nanoelectronics devices.1 aAher, Rahul1 aBhorde, Ajinkya1 aSharma, Priyanka1 aNair, Shruthi1 aBorate, Haribhau1 aPandharkar, Subhash1 aRondiya, Sachin1 aChaudhary, Minakshi1 aGopinath, Chinnakonda1 aSuryawanshi, Sachin1 aMore, Mahendra1 aJadkar, Sandesh uhttp://library.ncl.res.in/content/hydrothermal-synthesis-rgo-pbbi2se4-composite-and-investigation-its-structural-chemical-and03243nas a2200241 4500008004100000245011700041210006900158260000800227300001600235490000700251520241500258100002402673700002002697700002002717700001802737700001602755700001902771700002102790700001902811700002102830700001902851856013102870 2019 eng d00aProbing the effect of selenium substitution in kesterite-Cu2ZnSnS4 nanocrystals prepared by hot injection method0 aProbing the effect of selenium substitution in kesteriteCu2ZnSnS cAUG a14781-147900 v303 a

In this paper, we report the effect of sulfur (S) substitution with selenium (Se) in CZTS nanocrystals prepared by hot injection method. The formation of kesterite-copper zinc tin sulfide (Cu2ZnSnS4, CZTS) and copper zinc tin selenide (Cu2ZnSnSe4, CZTSe) nanocrystals is confirmed by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) analysis. The XRD, TEM and atomic force microscopy (AFM) analysis shows an overall increase in average crystallite size upon Se substitution. AFM images revealed an increase in root mean square surface roughness (S-q) and average surface roughness (S-a) when S in CZTS is replaced by Se. The substitution of S by Se in host CZTS narrows the optical band gap from 1.56 to 1.03 eV. The ultraviolet photoelectron spectroscopy (UPS) analysis shows shift in valence band and conduction band edge in CZTSe compared to CZTS. The photocurrent density measurement in synthesized CZTSe thin films is similar to 4 to 5 times higher than CZTS thin films. The obtained results show that CZTSe can be a promising candidate as absorber material in photovoltaic applications.

1 aPandharkar, Subhash1 aRondiya, Sachin1 aBhorde, Ajinkya1 aNair, Shruthi1 aAher, Rahul1 aVairale, Priti1 aWaghmare, Ashish1 aNaik, Dhirsing1 aWaykar, Ravindra1 aJadhav, Yogesh uhttp://library.ncl.res.in/content/probing-effect-selenium-substitution-kesterite-cu2znsns4-nanocrystals-prepared-hot-injection02757nas a2200241 4500008004100000022001400041245014000055210006900195260000800264300001400272490000700286520189900293100002002192700002202212700002002234700001902254700001602273700003202289700002302321700002202344700002002366856012902386 2023 eng d a0020-166900aLead-free solid state mechanochemical synthesis of Cs2NaBi1-XFeXCl6 double perovskite: reduces band gap and enhances optical properties0 aLeadfree solid state mechanochemical synthesis of Cs2NaBi1XFeXCl cMAR a4861-48710 v623 a

Efficient and stable lead-free halide double perovskites (DPs) have attracted great attention for the future generation of electronic devices. Herein, we have developed a doping approach to incorporate Fe3+ ions into the Cs2NaBiCl6 crystal unit and reveal a crystallographic and optoelectronic study of the Cs2NaBi1-xFexCl6 double perovskite. We report a simple solid-state mechanochemical method that has a solvent-free, one-step, green chemistry approach for the synthesis of Cs2NaBi1-xFexCl6 phosphor. The analysis of powder X-ray diffraction (XRD) data determines the contraction of the lattice due to the incorporation of Fe3+ cations, and this effect is well supported by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and solid-state nuclear magnetic resonance spectroscopy (ss-NMR). The band gap is reduced with increasing Fe content owing to the strong overlap of the Fe-3d orbitals with Cl-3p orbitals and shift of the valence band maxima (VBM) toward higher energies, as confirmed by ultraviolet photoelectron spectroscopy (UPS) and density functional theory (DFT) analyses. Photoluminescence (PL) studies of Cs2NaBi1-xFexCl6 phosphors exhibit a large Stokes shift, broadband emission, and increased PL intensity more than ten times for 15% of Fe content phosphor with enhancement in the average decay lifetimes (up to 38 ns) compared to pristine Cs2NaBiCl6 DP. These results indicate that the transition of dark self-trapping of excitons (STEs) into bright STEs enhances yellow emission. XRD, UV, and thermo-gravimetric analysis (TGA) confirmed that the Cs2NaB1-xFexCl6 DPs have good structural and thermal stabilities. Our findings indicate that the doping of Fe3+ cations into the Cs2NaBiCl6 lattice is a constructive strategy to enhance significantly the optoelectronic properties of these phosphors.

1 aUdavant, Rohini1 aThawarkar, Sachin1 aRondiya, Sachin1 aShelke, Ankita1 aAher, Rahul1 aAjithkumar, Thalasseril, G.1 aCross, Russell, W.1 aDzade, Nelson, Y.1 aJadkar, Sandesh uhttp://library.ncl.res.in/content/lead-free-solid-state-mechanochemical-synthesis-cs2nabi1-xfexcl6-double-perovskite-reduces