Photoconductivity of a Low-Bandgap Conjugated Polymer

✍ Scribed by C. Soci; I.-W. Hwang; D. Moses; Z. Zhu; D. Waller; R. Gaudiana; C. J. Brabec; A. J. Heeger

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 297 KB
• Volume: 17
• Category: Article
• ISSN: 1616-301X
• DOI: 10.1002/adfm.200600199

✦ Synopsis

Abstract

The photoconductive properties of a novel low‐bandgap conjugated polymer, poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4__H__‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)], PCPDTBT, with an optical energy gap of E~g~ ∼ 1.5 eV, have been studied. The results of photoluminescence and photoconductivity measurements indicate efficient electron transfer from PCPDTBT to PCBM ([6,6]‐phenyl‐C61 butyric acid methyl ester, a fullerene derivative), where PCPDTBT acts as the electron donor and PCBM as the electron acceptor. Electron‐transfer facilitates charge separation and results in prolonged carrier lifetime, as observed by fast (t > 100 ps) transient photoconductivity measurements. The photoresponsivities of PCPDTBT and PCPDTBT:PCBM are comparable to those of poly(3‐hexylthiophene), P3HT, and P3HT:PCBM, respectively. Moreover, the spectral sensitivity of PCPDTBT:PCBM extends significantly deeper into the infrared, to 900 nm, than that of P3HT. The potential of PCPDTBT as a material for high‐efficiency polymer solar cells is discussed.