Figure 5. Luminescence yield.

(a), Measured external luminescence efficiency and extracted internal luminescence efficiency as a function of growth temperature. (b), Optically measured “I–V” curves obtained from external luminescence efficiency measurements. Here, Suns represents the intensity of the absorbed laser light (1-sun = 100 mW/cm²), and corresponds to the photogenerated current level. The quasi-Fermi level splitting (ΔE_F) represents the resulting V_OC that would occur to balance the photogenerated current.