Enhanced Efficiency and Stability in P3HT:PCBM Bulk Heterojunction Solar Cell by using TiO2 Hole Blocking Layer

ABSTRACTInsertion of TiO2 layer between Al negative electrode and active layer of bulk-heterojunction gave a high solar conversion efficiency and high stability. The TiO2 layer was prepared by spin-coating titanium(IV)isopropoxide (Ti(OC3H7)4) on active layer of blended P3HT:PCBM. The parallel resistance (Rp) is increased by inserting TiO2 layer leading to an increase in Voc. The TiO2 layer works as a hole blocking layer and prevents the physical and chemical damages by the direct contact between P3HT:PCBM active layer and Al electrode resulting in improvement of the parallel resistance and rectification. The efficiency of P3HT:PCBM bulk heterojunction cell with TiO2 hole blocking layer attained 4.05% with a Isc 9.72 mA/cm2, Voc 0.60 V, and FF 0.70 by using optimized TiO2 film thickness and ratio of P3HT:PCBM condition.