26729
Low Driving Voltage and High Mobility Ambipolar Field - Effect Transistors with PbS Colloidal Nanocrystals .
 Chemical: PbS
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: PbS 
Answer:
 Chemical: PbS