7442
The more empirical formulations to the efficiency limits provide estimates of 10 - 12 % , but the more fundamental descriptions suggest limits of 20 - 24 % to be reachable in single junctions , similar to the highest efficiencies obtained for crystalline silicon p - n junction solar cells .
 Chemical: silicon
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: silicon