Förster resonance energy transfer in organic photovoltaics devices fabricated by electric field assisted spray technique

Abstract

Thin films of the ternary polymer blend (donors PCE-10 and PCDTBT with the acceptor PC71BM in chlorobenzene) were fabricated by using spray coating technique without and with applied voltage to the nozzle during deposition. The increased absorption range from 400 nm to 800 nm indicates that Förster resonance energy transfer (FRET) is occurring for the films deposited under the electric field. This is also supported by photoluminescence measurements and suggesting that under the applied voltage the orientation of polymer chains are changing at desired distances to facilitate FRET phenomenon to occur due to repulsion between uniformly charged ultrafine droplets. The size of droplets further reduced at higher applied voltage. Absorption, photoluminescence, femtosecond transient absorption spectra and Kinetics traces were recorded to elucidate the role of applied DC voltages during the deposition of these films on photovoltaic performance of bulk heterojunction organic solar cell. The effect of FRET in polymer-polymer thin film under applied voltage during the deposition is observed, which indicates enhancement in the power conversion efficiency with the maximum value of 6.86% (Jsc of 15.81 mA/cm2 and Voc of 0.77 V) at an applied voltage of 750 V.