TY - JOUR
T1 - Controlling molecular conformation for highly efficient and stable deep-blue copolymer light-emitting diodes
AU - Hamilton, I.
AU - Chander, N.
AU - Cheetham, N.J.
AU - Suh, M.
AU - Dyson, M.
AU - Wang, X.
AU - Stavrinou, P.N.
AU - Cass, M.
AU - Bradley, D.D.C.
AU - Kim, Ji-Seon
PY - 2018/4/4
Y1 - 2018/4/4
N2 - We report a novel approach to achieve deep-blue, high-efficiency, and long-lived solution-processed polymer light-emitting diodes (PLEDs) via a simple molecular level conformation change of an emissive conjugated polymer. We introduce rigid β-phase segments into a 95% fluorene—5% arylamine copolymer emissive layer. The arylamine moieties at low density act as efficient exciton formation sites in PLEDs, whereas the conformational change alters the nature of the dominant luminescence from a broad, charge transfer like emission to a significantly blue-shifted and highly vibronically structured excitonic emission. As a consequence, we observe a significant improvement in the Commission International de L’Eclairage (x, y) coordinates from (0.149, 0.175) to (0.145, 0.123) while maintaining high efficiency and improved stability. We achieve a peak luminous efficiency, η = 3.60 cd/A, and a luminous power efficiency, ηw = 2.44 lm/W, values that represent state-of-the-art performance for single copolymer deep-blue PLEDs. These values are 5-fold better than for otherwise-equivalent, β-phase poly(9,9-dioctylfluorene) PLEDs (0.70 cd/A and 0.38 lm/W). This report represents the first demonstration of the use of molecular conformation as a simple but effective method to control the optoelectronic properties of a fluorene copolymer; previous examples have been confined to homopolymers.
AB - We report a novel approach to achieve deep-blue, high-efficiency, and long-lived solution-processed polymer light-emitting diodes (PLEDs) via a simple molecular level conformation change of an emissive conjugated polymer. We introduce rigid β-phase segments into a 95% fluorene—5% arylamine copolymer emissive layer. The arylamine moieties at low density act as efficient exciton formation sites in PLEDs, whereas the conformational change alters the nature of the dominant luminescence from a broad, charge transfer like emission to a significantly blue-shifted and highly vibronically structured excitonic emission. As a consequence, we observe a significant improvement in the Commission International de L’Eclairage (x, y) coordinates from (0.149, 0.175) to (0.145, 0.123) while maintaining high efficiency and improved stability. We achieve a peak luminous efficiency, η = 3.60 cd/A, and a luminous power efficiency, ηw = 2.44 lm/W, values that represent state-of-the-art performance for single copolymer deep-blue PLEDs. These values are 5-fold better than for otherwise-equivalent, β-phase poly(9,9-dioctylfluorene) PLEDs (0.70 cd/A and 0.38 lm/W). This report represents the first demonstration of the use of molecular conformation as a simple but effective method to control the optoelectronic properties of a fluorene copolymer; previous examples have been confined to homopolymers.
KW - deep-blue, polymer light-emitting diodes, β-phase, polyfluorenes, copolymers
KW - copolymers
KW - deep-blue
KW - polymer light-emitting diodes
KW - polyfluorenes
KW - β-phase
KW - beta-phase
UR - http://www.scopus.com/inward/record.url?scp=85044963551&partnerID=8YFLogxK
U2 - 10.1021/acsami.8b00243
DO - 10.1021/acsami.8b00243
M3 - Article
C2 - 29508604
VL - 10
SP - 11070
EP - 11082
JO - ACS Applied Materials & Interfaces
JF - ACS Applied Materials & Interfaces
SN - 1944-8244
IS - 13
ER -