We synthesized cesium tin bromide (CsSnBr3), a solar energy conversion material with a band gap of 1.7 eV, using both solution cooling method and high temperature melt method. This was followed by the study of the basicity of interfacial Br- sites on CsSnBr3 by reacting the synthesized crystals with boron trifluoride (BF3) and tris(pentafluorophenyl)borane (B(C6F5)3). XPS data give F 1s to Br 3d peak area ratios of 0.69 and 0.80 for BF3 and B(C6F5)3 treated CsSnBr3, respectively. These correspond to surface coverages of 190% for BF3 45% for B(C6F5)3. We interpreted the desorption temperature of the BF3 treated sample to be 230 °C from temperature programmed desorption (TPD) data, which implies a boron- bromine bond strength of 132 kJ/ mol.
Worcester Polytechnic Institute
Major Qualifying Project
Chemistry and Biochemistry