The conformational distribution and mutual interconversion of thermally activated delayed fluorescence (TADF) emitters significantly affect the exciton utilization. However,t heir influence on the photophysics in amorphous film states is still not knownd ue to the lacko fasuitable quantitative analysis method. Herein, we used temperaturedependent time-resolved photoluminescence spectroscopyt o quantitatively measure the relative populations of the conformations of aT ADF emitter for the first time.W ef urther propose an ew concept of "self-doping" for realizing highefficiency nondoped OLEDs.Interestingly,this "compositionally" pure film actually behaves as afilm with adopant (quasiequatorial form) in am atrix (quasi-axial form). The concentration-induced quenching that may occur at high concentrations is thus expected to be effectively relieved. The "selfdoping" OLED prepared with the newly developed TADF emitter TP2P-PXZ as an eat emitting layer realizes ah igh maximum external quantum efficiency of 25.4 %a nd neglectable efficiency roll-off.

The buckling deformation and stress distribution of the tubing nearby the packer would be seriously influenced by the packer constraints. This paper focused on the Strength analysis of transitional segment. The method to calculate the buckling deformation and the equivalent stress of transitional segment were derived considering the tubing boundary and continuity condition, adopting the fourth-order nonlinear ordinary differential equations and helical buckling strength method. This study makes up for the weakness of traditional stress analysis of the buckling tubing nearby the packer in vertical well, improves the pertinence and accuracy of stress analysis of buckling tubing. The results of analysis show that with the axial pressure increasing lead to the length of the transitional segment irregular fluctuations and the maximum equivalent stress increasing. The equivalent stress would gradually reduce and finally approach a constant.