13889
In this study , the presence of excited - state and charge - separated species , including singlet excitons , polymer polarons and free charges , generated in rr - P3HT / PCBM nanoparticles was identified through visible pump and visible / near - infrared probe femtosecond transient absorption spectroscopy at a range of electron acceptor concentrations .
 Chemical: P3HT; Chemical: PCBM
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: P3HT; Chemical: PCBM