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Nature of Non‐emissive Black Spots in Polymer Light‐Emitting Diodes by In‐Situ Micro‐Raman Spectroscopy
Author(s) -
Kim J.S.,
Ho P.K.H.,
Murphy C.E.,
Baynes N.,
Friend R.H.
Publication year - 2002
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/1521-4095(20020205)14:3<206::aid-adma206>3.0.co;2-j
Subject(s) - materials science , pinhole (optics) , light emitting diode , optoelectronics , black spot , raman spectroscopy , diode , spots , luminance , optics , chemistry , physics , horticulture , biology
Both intrinsic and extrinsic degradation mechanisms limit the long‐term stability of light‐emitting diodes (LEDs). Here the nature of black spots formed on such devices is examined in detail. It is concluded that black spots, which form around pinhole defects (see Figure for mechanism of pinhole defect formation at grain boundaries), cause a reduction of total luminance output but not of device efficiency.