Table 1 Performance of OLEDs with various light outcoupling structures

Light outcoupling structures		Lateral dimension (\({r}_{{{{\rm{LOS}}}}}/{r}_{{{{\rm{EA}}}}}\))	EQE (%)	EQE₃₀ (%)	CE (cd A⁻¹)	Lambertian factor^a (\({f}_{{{{\rm{LB}}}}}\))
Distributed Bragg reflector (DBR) (Sim.)	1 dyad	Semi-infinite	18.45	8.576	168.8	0.45
	2 dyads	Semi-infinite	19.64	8.795	174.1	0.46
	3 dyads	Semi-infinite	15.88	6.525	139.7	0.47
Microstructure array (Sim.)	Microcone	Semi-infinite	45.60	11.70	164.6	0.82
Microstructure array (Sim.)	Microlens	Semi-infinite	50.04	12.85	162.6	0.91
Scattering layer (Sim.)	\({\mu }_{{{{\rm{s}}}}}\) = 100 mm⁻¹ \({d}_{{{{\rm{s}}}}}\) = 1.4 μm \({n}_{{{{\rm{s}}}}}\) = 1.4	Semi-infinite	55.41	14.33	168.5	0.98
LP₃₀-LOS (Exp.)		1.945 (\({r}_{{{{\rm{RA}}}}}/{r}_{{{{\rm{EA}}}}}\) = 2)	48.04	16.38	192.2	0.74
LP₃₀-LOS (Exp.)		2.633 (\({r}_{{{{\rm{RA}}}}}/{r}_{{{{\rm{EA}}}}}\) = 3)	57.20	18.43	216.5	0.85

^aThe Lambertian factor (\({f}_{{{{\rm{LB}}}}}\)) is defined by the ratio of the total optical power output towards the upper hemisphere of an OLED under test to that of a Lambertian source with the same normal-direction intensity as that of the OLED under test. The ratio of power efficiency between two light sources 1 and 2 is then proportional to [\({I}_{1}(\theta=0)/{I}_{2}(\theta=0)\)] [\({f}_{{{{\rm{LB}}}}1}/{f}_{{{{\rm{LB}}}}2}\)] and thus to \(\left({\eta }_{{{{\rm{CE}}}}1}/{\eta }_{{{{\rm{CE}}}}2}\right)\left({f}_{{{{\rm{LB}}}}1}/{f}_{{{{\rm{LB}}}}2}\right)\). The ratio of EQE between two light sources 1 and 2 is more subtle than the case of PE due to the effect of spectral distribution, but it essentially follows the similar proportionality. For example, EQE of Source 1 can even be smaller than that of Source 2 even though Source 1 has higher CE than Source 2, provided that \({f}_{{{{\rm{LB}}}}}\) of Source 1 is much smaller than that of Source 2.

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