A　heterojunction　solar　cell　based　on　poly　(hexylthiophene)　(P3HT)　and　fullerene　(PCBM)　was　fabricated.　The　hole　transport　layer　and　the　active　layer　were　prepared　by　spraying.　The　effect　of　the　substrate　temperature　on　the　morphology　of　the　active　layer　and　the　performance　of　the　device　were　studied.　The　results　show　that　the　film　roughness　decreases　and　the　absorption　rate　increases　when　the　substrate　temperature　increases.　And　when　the　substrate　temperature　is　130°C,　the　device　performance　is　optimized　and　the　efficiency　of　a　25　mm2-size　device　is　2.09%.　The　small　size　devices　were　combined　in　series　and　parallel　to　achieve　a　11.2　cm2-size　large　area　organic　solar　array　and　the　conversion　efficiency　is　1.83%.　It　is　found　that　the　area　is　increased　by　44.8　times,　while　the　efficiency　loss　is　less　than　13%.