Nanostar and nanonetwork crystals were prepared from fully conjugated poly(3-(2-ethylhexyl)-thiophene)-block-polythiophene (P3EHT-b-PT) via a simple INCP process. The structural conformation of the nanocrystals was investigated in detail, revealing that with an increase in the block length of PT, the morphology of the nanocrystals changed from nanospheres to nanorods, nanostars, and to nanonetworks.