Synthesis and Spectroscopic Characterization of Dual Absorption BODIPY Type Dyes and their Light Harvesting Application in Polymer-Based Bulk Hetrojunction Organic Photovoltaics

We reported the synthesis and characterization of two new BODIPY type dyes with fluorine-bridged two chromophores, boron-dipyrromethene (BDP) and boron-diindomethene (BDI). Each of BODIPY dyes 7a and 7b has two strong absorption bands around 500 and 600 nm bearing high extinction coefficients (76,000 M(-1)cm(-1) for 7a and 71,000 M(-1)cm(-1) for 7b at 501 nm; 115,000 M(-1)cm(-1) for 7a and 110,000 M(-1)cm(-1) for 7b at 603 nm). For light harvesting enhancement of solar cell, we have fabricated bulk heterojunction photovoltaics with various weight percentages of 7a as dopant dye in P3HT:PCBM blends in attempting to improve power conversion efficiency of solar energy.