Long-range exciton dissociation in layered organic solar cells

Abstract

Long-range charge transfer in a donor-spacer-acceptor system is observed. When tris-8-hydroxy-quinolinato aluminum ͑Alq 3 ͒ is used as a spacer between copper phthalocyanine ͑CuPc, donor͒ and C 60 ͑acceptor͒, electron transfer over 14 nm from CuPc to C 60 and hole transfer over 30 nm from C 60 to CuPc occur. Two charge transfer mechanisms are identified by this study: electron tunneling via gap states of Alq 3 ͑the lowest unoccupied molecular orbitals of Alq 3 act as an energy barrier͒ and hole transport via the highest occupied molecular orbitals of Alq 3 , which act as step-stone levels. A thin spacer with suitable energy levels is suggested to improve the power conversion efficiency by inhibiting the recombination of geminate pair polarons.

Effects of multiple heat treatment cycles on structure, optical and electrical properties of indium-tin-oxide thin films

“…Compared to other transparent conductive oxide (TCO) such as fluorine or antimony doped tin oxide (FTO and ATO), ITO possesses a better optical transmission and a higher charge carrier concentration of up to a factor of two [1,2]. Due to these good characteristics, ITO thin film has been broadly used in many opto-electronic applications such as solar cells [3][4][5], organic light-emitting diodes [6,7], electrochromic panels [8] and liquid crystal displays [9]. Studies have been performed to optimize the conductivity and transmittance of ITO thin film for high property reproducibility during fabrication processes like DC and RF sputtering [10][11][12][13], electron beam evaporation [14] and physical vapor deposition [15].…”

Comparative Study of Non-Annealing and Annealing on Properties of ITO Deposited by RF Magnetron Sputtering

“…Transparent conducting oxide films are critical components for advance in technological optoelectronic device such as solar cells [1], smart windows [2] and organic light emitting devices [3]. Indium tin oxide (ITO) films are the most promising materials for those potential technological and industrial applications due to their high optical transparency in the visible spectrum combined with very high electrical conductivity.…”