To get insight into how the OEEFs affect the properties of the spectrum, we first analyzed the variation of E 0 and E 1 under F X . As shown in Figure , increasing the field strength raises the energy of both the S 0 and S 1 states, but the energy change differs between the two states. Conversely, decreasing the field strength leads to a decrease of both E 0 and E 1 . Similar to the case of polar solvents, the S 1 state is more sensitive to the field than the S 0 state, and the change of E 1 is much larger than the change of E 0 for the same field strength. Intriguingly, the vertical emission energy (E F = E 1 -E 0 ) responds linearly to the field strength of F X , with a larger field leading to a larger E F . The relationship between E F and F X can be fitted with a simple equation: E F = 81.59 F X + 3.00. The linear and continuous dependence of E F on the electric field indicates the feasibility of intentional and accurate color tuning through control of the local electric field, as well as the ability to detect electric field strength through the spectrum. In order to understand why S 1 state is more sensitive to the field, the values of both μ 0 and μ 1 under F X were calculated. To facilitate subsequent discussions, the X component of μ 1 and μ 0 is denoted as μ 1X and μ 0X , respectively. As shown in Figure , both μ 1X (red line) and μ 0X (blue line) are negative within the applied field strength (0.0075 a.u.). Additionally, the magnitude of μ 1X is always larger than μ 0X , and both μ 0X and μ 1X respond linearly to the field strength. Finally, the difference between μ 1X and μ 0X remains nearly unchanged. The negative value of the dipole moment indicates that a negative field stabilizes the dipole moment and lowers its energy, while a positive field has the opposite effect. The larger magnitude of μ 1X compared to μ 0X explains the greater field effect of F X on the S 1 state than the S 0 state. The linear response of E F to F X , along with the consistent difference between μ , the dipole moment analysis gives a well explanation of the effect of OEEFs (refer to Note 2 for a more quantitative discussion in SI), reminiscent of the case of the selectivity control of Diel-Alder reactions by OEEFs. Scheme 3. Three possible interaction modes of OEEFs.