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An X-ray detector system was fabricated with an organic small molecule photodetector and a terbium-doped gadolinium oxysulfide (Gd2O2S:Tb) scintillating screen. Though the microsphere cluster structure of the Gd2O2S film had advantage in low material cost, wavelength matching to the proper photodetector is challenging due to its scintillating performance property in the relatively narrow emission spectrum range. To tune the absorption spectrum of the organic photodetector to that of the emission spectrum of the Gd2O2S, a microcavity effect was applied by controlling the thickness of the C60 layer. The peak wavelength of the absorption spectrum was tuned over a broad region of wavelengths, from 461 nm to 776 nm. The fabricated X-ray detector system was demonstrated in a medical X-ray radiography system.

A thin film encapsulation layer was fabricated through two-sequential chemical vapor deposition processes for organic light emitting diodes (OLEDs). The fabrication process consists of laser assisted chemical vapor deposition (LACVD) for the first silicon nitride layer and laser assisted plasma enhanced chemical vapor deposition (LAPECVD) for the second silicon nitride layer. While SiNx thin films fabricated by LAPECVD exhibits remarkable encapsulation characteristics, OLEDs underneath the encapsulation layer risk being damaged during the plasma generation process. In order to prevent damage from the plasma, LACVD was completed prior to the LAPECVD as a buffer layer so that the laser during LACVD did not damage the devices because there was no direct irradiation to the surface. This two-step thin film encapsulation was performed sequentially in one chamber, which reduced the process steps and increased fabrication time. The encapsulation was demonstrated on green phosphorescent OLEDs with I–V-L measurements and a lifetime test. The two-step encapsulation process alleviated the damage on the devices by 19.5% in external quantum efficiency compared to the single layer fabricated by plasma enhanced chemical vapor deposition. The lifetime was increased 3.59 times compared to the device without encapsulation. The composition of the SiNx thin films was analyzed through Fourier-transform infrared spectroscopy (FTIR). While the atomic bond in the layer fabricated by LACVD was too weak to be used in encapsulation, the layer fabricated by the two-step encapsulation did not reveal a Si–O bonding peak but did show a Si–N peak with strong atomic bonding.

As the efficiency of organic solar cells has been consistently improved, interest is being raised to understand degradation mechanisms inside the solar cells. Among many factors that affect solar cell deterioration, light is the most crucial factor in the degradation mechanism. Here we report degradation under the continuous light-induced conditions for PTB7:PC70BM organic solar cells during the first 24 h with maintaining the temperature at 25 °C. It revealed 30% of initial performance drop after 24 h of light-induced aging, mostly through a decrease in JSC and FF. The morphological and electrical characteristics of the active layer and devices were investigated by atomic force microscopy, impedance spectroscopy, and temperature-dependent current density–voltage characteristics to figure out the origin of the photo-induced degradation. As a result, the light-induced traps were found to be a primary cause of loss. Furthermore, this trap formation was observed with an energy of 78 meV leading to trapped charge limited conduction properties and electrical degradation of solar cells.