Novel D–A–D type dyes based on BODIPY platform for solution processed organic solar cells

Abstract

Four novel symmetrical donor–acceptor–donor (D–A–D) type boron dipyrromethene (BODIPY) based dyes, namely BDP1–4, featuring an electron-withdrawing BODIPY motif as the central core, and several types of electron-donating segments, including thiophene, bithiophene, fluorene and carbazole, flanked at its 2,6-positions as terminal groups were synthesized and characterized. All of these BDPs exhibit panchromatic absorption covering the wavelength range 300–900 nm with high extinction coefficients (0.78 × 105 to 1.22 × 105 cm−1 M−1) and relatively lower HOMO energy levels from −5.17 to −5.48 eV. Furthermore, BDP1–4 show good thermal stabilities, excellent film-forming abilities and low fluorescent quantum yields. BDP2 flanking with bithiophene units demonstrates superior charge transport property and favorable nanoscale morphology relative to BDP1, BDP3 and BDP4. The power conversion efficiency (PCE) values of the organic solar cells (OSCs) based on the BDPs/PC61BM (1:0.5, w/w) are 1.49% for BDP1, 2.15% for BDP2, 1.06% for BDP3 and 1.56% for BDP4, respectively.