The bandgap energy as a function of temperature has been determined for lead iodide. The monocrystal was obtained in a vacuum sealed quartz ampoule inside a vertical furnace by Bridgman's method. The optical transmittance measurement enables to evaluate the values of Eg. By a fitting procedure of Eg as a function of temperature is possible to extract the parameters that govern its behavior. The variation of Eg with temperature was determined as: Eg(T) = Eg(0) - <FONT FACE="Symbol">a</FONT>T2/(<FONT FACE="Symbol">a</FONT> + T), with: Eg(0) = (2.435 <FONT FACE="Symbol">±</FONT> 0.008) eV, <FONT FACE="Symbol">a</FONT> = (8.7 <FONT FACE="Symbol">±</FONT> 1.3) x 10-4 eV/K and <FONT FACE="Symbol">a</FONT> = (192 <FONT FACE="Symbol">±</FONT> 90) K. The bandgap energy of lead iodide at room temperature was found to be 2.277 <FONT FACE="Symbol">±</FONT> 0.007 eV.
optical properties; lead iodide; Bridgman's Method
