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Proceedings Paper

Photocurrent in organic semiconductor/halide perovskite heterostructures: Impact of grain size on charge generation efficiency (Conference Presentation)
Author(s): Colin Tyznik; James Lee; Jeni Sorli; John Anthony; Yueh-Lin Loo; Oana Jurchescu

Paper Abstract

The emergence of hybrid organic inorganic perovskites (HOIPs) perovskites, with their higher charge carrier mobilities and tunable bandgap, coupled with low-cost processability, has opened new avenues of research in optoelectronic applications. Various devices based on HOIPs, including photovoltaics, light-emitting diodes, transistors or photodetectors have been reported. Here, we explore the photocurrent properties in heterostructures consisting of small molecule semiconductors and HOIPs. Bilayer devices can use bandgap alignment to improve carrier separation and collection. The HOIP CH3NH3PbI3-xClx was the primary photoactive layer and electron transport layer, while the hole transport layer was 2,8-Difluoro-6,13-Bis(triisopropylsilylethynyl) anthradithiophene (diF-TIPS-ADT). We found that the responsivity of the bilayer device was six times greater than neat perovskite film, reaching values as high as 5.1 A/W, and detectivity more than doubled, to 2.9*10^11 Jones. We further tuned the interfacial processes by altering the microstructure of the organic semiconductor layer and evaluated the photocurrent response. We found that treatment of the gold contacts with (2,3,4,5,6)-Pentafluorothiophenol (PFBT) resulted in large grains within the organic semiconductor. Consequently, responsivity was over 15 times greater than that of the neat perovskite film, reaching values of 13.7 A/W, and detectivity improved by 8 times to 8.4*10^11 Jones. Grazing-incidence X-ray diffraction measurements indicate that diF-TIPS-ADT is preferentially oriented with its (001) plane parallel to the substrate in both sample types. The observed performance improvement thus cannot originate from differences in the interfacial coupling related to molecular orientation. Instead, we believe differences in trapping at grain boundaries is responsible for the changes in charge generation efficiency.

Paper Details

Date Published: 10 September 2019
Proc. SPIE 11097, Organic and Hybrid Field-Effect Transistors XVIII, 110970S (10 September 2019); doi: 10.1117/12.2528956
Show Author Affiliations
Colin Tyznik, Wake Forest Univ. (United States)
James Lee, Wake Forest Univ. (United States)
Jeni Sorli, Princeton Univ. (United States)
John Anthony, Univ. of Kentucky (United States)
Yueh-Lin Loo, Princeton Univ. (United States)
Oana Jurchescu, Wake Forest Univ. (United States)

Published in SPIE Proceedings Vol. 11097:
Organic and Hybrid Field-Effect Transistors XVIII
Iain McCulloch; Oana D. Jurchescu, Editor(s)

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