We report dramatic improvements in the stability and crystallinity arising from partial fluorination of soluble anthradithiophene derivatives. These fluorinated materials still behave as p-type semiconductors but with dramatic increases in thermal and photostability compared to the non-fluorinated derivatives. The triethylsilyl-substituted material forms highly crystalline films even from spincast solutions, leading to devices with maximum hole mobility greater than 1.0 cm(2)N s. In contrast, the triisopropylsilyl derivative forms large, high-quality crystals that could serve as the substrate for transistor fabrication. For this compound, mobility as high as 0.1 cm(2)N S Was measured on the freestanding crystal.