We construct an apparatus to spatially resolve and correlate photoluminescence and photoconductivity in materials and their devices. For examples, we use this apparatus to map photoconductivity in nanocrystalline and organic materials and in fabricated solar photovoltaics to understand inhomogeneities that are intentionally introduced at the material or device level or that develop during device operation.
Schematic of the correlative, spatially resolved photoluminescence and photoconductivity apparatus. This apparatus was used to measure (left) photoconductivity in semiconductor nanocrystal thin films with periodic modulations in thickness formed by self-assembly; (middle) the short circuit current in PCBM/P3HT bulk heterojunction solar cells to correlate ageing in organic solar cells with degradation in device performance; the effects of ageing are prevented by introduction of a compatibilizer composed of an oligothiophene tethered fullerene; and (right) photocurrent enhancement in solar cells arising from light trapping in photonic structures introduced by wrinkles and folds in the underlying substrate upon (blue) 488 nm and (red) 750 nm excitation. [scale bar 5 um].
Multiscale Periodic Assembly of Striped Nanocrystal Superlattice Films on a Liquid Surface
, Angang Dong, Jun Chen, Soong Ju Oh, Weon-kyu Koh, Faxian Xiu, Xingchen Ye, Dong-Kyun Ko, Kang L. Wang, Cherie R. Kagan, and Christopher B. Murray, Nano Letters, 11
(2), 841-846, (2011)
Small-Molecule Thiophene-C60 Dyads As Compatibilizers in Inverted Polymer Solar Cells
, Jong Bok Kim, Kathryn Allen, Soong Ju Oh, Stephanie Lee, Michael F. Toney, Youn Sang Kim, Cherie R. Kagan, Colin Nuckolls, and Yueh-Lin Loo, Chemistry of Materials, 22
(20), pp 57625773 (2010)
Diketopyrrolopyrrole-based p-bridged Donor-Acceptor Polymer for Photovoltaic Applications
Wenting Li, Taegweon Lee, Soong Ju Oh, and Cherie R. Kagan, ACS Applied Materials and Interfaces
(10) 3874-3883 (2011)
Wrinkles and deep folds as photonic structures in photovoltaics
Jong Bok Kim, Pilnam Kim, Nicolas C. Pιgard, Soong Ju Oh, Cherie R. Kagan, Jason W. Fleischer, Howard A. Stone and Yueh-Lin Loo, Nature Photonics