To analyze the time profiles of TTA-UC emission under different excitation intensities, we used a method detailed in the Supporting Information with Figure and Table . The 𝜏 ( and the dimensionless parameter of 𝛽 (Eq. 4) are obtained from the time-dependent UC emission intensity, 𝐼 !" (𝑡): Figure and 2d show the excitation light intensity dependence of 𝛽 in the PtOEP/TAB and PtOEP/DPA samples, respectively. We found that there is a nonlinear relationship between 𝛽 and excitation light intensity. Here, 𝛽 is expressed by Eq. ( ):