ine ▁sil icon ▁▁ ▁Un like ▁conventional ▁cry st all ine ▁sil icon ▁cells ▁based ▁on ▁a ▁hom oj unction , ▁the ▁structure ▁of ▁C IG S ▁cells ▁is ▁a ▁more ▁complex ▁heter oj unction ▁system . ▁A ▁direct ▁band g ap ▁material , ▁C IG S ▁has ▁very ▁strong ▁light ▁absor ption ▁and ▁a ▁layer ▁of ▁only ▁ 1 – 2 ▁mic rom eters ▁( µ m ) ▁is ▁enough ▁to ▁abs orb ▁most ▁of ▁the ▁sun light . ▁By ▁comparison , ▁a ▁much ▁greater ▁thick ness ▁of ▁about ▁ 1 6 0 – 1 9 0   µ m ▁is ▁required ▁for ▁cry st all ine ▁sil icon . ▁ ▁The ▁active ▁C IG S - layer ▁can ▁be ▁depos ited ▁in ▁a ▁pol yc ry st all ine ▁form ▁directly ▁onto ▁mol y b den um ▁( Mo ) ▁co ated ▁on ▁a ▁variety ▁of ▁several ▁different ▁substr ates ▁such ▁as ▁glass ▁sheets , ▁steel ▁bands ▁and ▁pl astic ▁fo ils ▁made ▁of ▁poly im ide . ▁This ▁uses ▁less ▁energy ▁than ▁sm el ting ▁large ▁amounts ▁of ▁quart z ▁sand ▁in ▁electric ▁furn aces ▁and ▁growing ▁large ▁cry st als , ▁necessary ▁for ▁conventional ▁sil icon ▁cells , ▁and ▁thus ▁reduces ▁its ▁energy ▁pay back ▁time ▁significantly . ▁Also ▁unlike ▁cry st all ine ▁sil icon , ▁these ▁substr ates ▁can ▁be ▁flexible . ▁ ▁In ▁the ▁highly ▁compet itive ▁P V ▁industry , ▁pressure ▁increased ▁on ▁C IG S ▁manufact ur ers , ▁leading ▁to ▁the ▁bank rupt