Does a piezoelectric organic substance exist?
I think your question is a bit specific, but piezoelectric organic substances do exist. There was a paper in nature that researchers at Berkeley published.

Please see the following journal article:
http://www.nature.com/nnano/journal/v7/n6/full/nnano.2012.69.html#affil-auth

Also see the following public article:
http://www.extremetech.com/extreme/129389-berkeley-scientists-turn-harmless-virus-into-piezoelectric-generator