Thin film transistors and solar cells from polycrystalline silicon suffer from the influence of grain boundary charges. This contribution reviews three possibilities to suppress these charges: (i) by the selection of specially oriented grain boundaries in small-grained silicon. Analysis of solar cells demonstrates that (110)-textured films must contain electrically low-active boundaries. (ii) Special laser crystallization yields large-grained Si of excellent quality. (iii) Transfer techniques allow one to fabricate single crystal films on foreign substrates. In addition to these three methods, we discuss joined-wafer silicon for growth of single crystalline Si films and layers of essentially unlimited size.