Degradation of the photoluminescence of ZnTPP and ZnTPP-C$_{60}$ thin films under gamma irradiation

Porphyrins and their fullerene complexes are promising materials for organic photovoltaic structures. However, the stability of the properties of organic components under hard radiation is poorly studied. Here, the influence of $\gamma$ irradiation with medium (about 10$^4$ Gy) and large (10$^7$ Gy) doses on the photoluminescence of thin structurally perfect films of both pure porphyrin ZnTPP and ZnTPP-C$_{60}$ composite films in the molar ratio of 1.3: 1 is investigated. It is shown that the intensity of the electronic radiative transition (626 nm) decreases under the effect of $\gamma$ irradiation, and the dose dependence is threshold. The threshold dose is $\sim$20 kGy for the ZnTPP films. The intensity of the electron-vibrational part of the spectral dependence of the PL (670–690 nm) for both types of samples decreased at initial irradiation doses and decreases less with a further increase in the irradiation dose than for the purely electron transition. The addition of a fullerene in nanocomposite films increases the threshold dose, after which the PL of the films started to degrade, by a factor of $\sim$2.5. Herewith, the spectral components of the PL associated with the manifestation of the radiation transition of the fullerene C$_{60}$ are more stable under $\gamma$ irradiation.