21604
The n - doping proceeds via anion - induced electron transfer between the iodide on FPI and the fullerene in the solid state .
 Chemical: iodide; Chemical: FPI; Chemical: fullerene
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: iodide; Chemical: FPI; Chemical: fullerene