Fabrication of P3HT/PCBM bulk heterojunction solar cells with DNA complex layer

This work demonstrates the use of deoxyribose nucleic acid - hexadecyl trimethyl ammonium (DNA-CTMA) thin-film as a hole transport layer in P3HT/PCBM (poly(3-hexylthiophene)/(1-(3-methoxycarbonyl) propyl-1-phenyl [6,6]C61) bulk heterojunction polymer solar cell. DNA-CTMA complex thin-film as a potential replacement of commonly used poly(3,4-ethylene-dioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) provides various advantages. While the band gap of PEDOT:PSS is about 1.7 eV and its absorption band overlaps with that of P3HT reducing photocurrent, the band-gap of the DNA complex layer was measured to be about 4.1 eV and the film showed transmittance greater than 90 % over the broad spectrum of UV and visible light. The lowest unoccupied molecular orbital level of about 1.1 eV provides much more efficient electron blocking than PEDOT:PSS potentially reducing recombination at anode side. In addition, butanol solution of the DNA-CTMA complex easily wets any oxide surface effectively forming uniform thin films. P3HT/PCBM bulk heterojunction solar cells fabricated with a DNA-CTMA layer showed rectifying behavior under dark and a photovoltage over 200 mV under AM1.0 light exposure.