Tuesday 03 Sep 2013Photoconductive response in charge-transfer interfaces with high quantum efficiency

Dr Helena Alves - University of Lisbon

Laver LT6 11:00-12:00

Abstract: Organic semiconductors have unique optical, mechanical and electronic properties that can be combined with customized chemical functionality. In the crystalline form, determinant features for electronic applications such as molecular purity, the charge mobility or the exciton diffusion length, reveal a superior improved performance when compared with materials in a more disordered form (1). Combining crystals of two different conjugated materials has even enable a new 2D electronic system (2). However, the use of organic single crystals in devices is still limited to a few applications, such as field-effect transistors. Here we show for the first time the photoconductivity behaviour of single-crystal charge transfer interfaces. The system composed of rubrene and 7,7,8,8-tetracyanoquinodimethane presents a responsivity reaching 1 A/W, corresponding to an external quantum efficiency of nearly 100%. A similar approach, with a hybrid structure of a PCBM film and rubrene single crystal also presents high responsivity, with extended action towards the near IR. These results opens the possibility of using organic single-crystal interfaces in photonic applications.

[1] H. Najafov et al., Nature Mat. 9, 938 (2010).
[2] H. Alves et al., Nature Mat. 7, 575 (2008).
[3] H. Alves et al, Nature Comm. 4, (2013), doi:10.1038/ncomms2890.

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