IMPROVEMENT IN POWER CONVERSION EFFICIENCY IN CONJUGATED POLYMER MODIFIED PTB7-PC6OBM BASED BULK HETEROJUNCTION SOLAR CELLS

摘要

In the present invention, improved bulk heterojunction solar cells based on modified PTB7-PC60BM are disclosed wherein the existing electron donor low band gap conjugated polymer poly[4,8-bis[{2-ethylhexyl) oxy]benzo[1,2- b:4,5-b]dithiophene-2,6-diyl][3- fluoro-2-[(2-ethylhexyl) carbonyl] thieno[3,4-b]thiophenediyl] (herein after called PTB7) has been modified by another low band gap polymer poly[9-{1-octylnonyl)-9H-carbazole-2,7-diyl]- 2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (herein after called PCDTBT) to enhance its spectral response that is absorbing in the larger wavelength spectra as compared to that of individual PTB7 and PCDTBT, Further modified PTB7 viz. PTB7+PCDTBT has been used in combination with PC60BM acceptor, which shows power conversion efficiency (PCE) in the range of 2.5-6% as compared to PCE of 3% & 2% obtained in PTB7/PC60BM & PCDTBT/PC60BM active layer in the polymer solar cell. Besides that, the present invention also addresses the development of cost effective & efficient solar cells as PC60BM is cheaper than PC70BM which is currently used with the low band gap polymers for similar PCE achievement.