Perfluorododecyl iodide (I-PFC12) is of interest for area-selective deposition (ASD) applications as it exhibits intriguing properties such as ultralow surface energy, the ability to modify silicon’s band gap, low surface friction, and suitability for micro-contact patterning. Traditional photolithography is struggling to reach the required critical dimensions. This study investigates the potential of using I-PFC12 as a way to produce contrast between the growth area and non-growth areas of a surface subsequent to extreme ultraviolet (EUV) exposure. Once exposed to EUV, the I-PFC12 molecule should degrade with the help of the photocatalytic substrate, allowing for the subsequent selective deposition of the hard mask. The stability of a vapor-deposited I-PFC12 self-assembled monolayer (SAM) was examined when exposed to ambient light for extended periods of time by using X-ray photoelectron spectroscopy (XPS). Two substrates, SiO₂ and TiO₂, are investigated to ascertain the suitability of using TiO₂ as a photocatalytic active substrate. Following one month of exposure to light, the atomic concentrations showed a more substantial fluorine loss of 10.2% on the TiO₂ in comparison to a 6.2% loss on the SiO₂ substrate. This more pronounced defluorination seen on the TiO₂ is attributed to its photocatalytic nature. Interestingly, different routes to degradation were observed for each substrate. Reference samples preserved in dark conditions with no light exposure for up to three months show little degradation on the SiO₂ substrate, while no change is observed on the TiO₂ substrate. The results reveal that the I-PFC12 SAM is an ideal candidate for resistless EUV lithography.

2,2′,7,7′-Tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (Spiro-OMeTAD) is widely used as a hole-transporting material in perovskite solar cells (PSCs); however, its intrinsic thermal stability remains insufficiently understood. Here, the thermal stability and high-temperature behaviour of pristine Spiro-OMeTAD films prepared by solution processing and vacuum deposition are systematically investigated using real-time and standard x-ray photoelectron spectroscopy, with annealing temperatures up to 500 °C under ultra-high vacuum. Spiro-OMeTAD films deposited on different substrates exhibit similar chemical environments and photoemission characteristics, demonstrating that the surface chemistry is largely insensitive to deposition method and substrate. Pristine Spiro-OMeTAD remains chemically stable up to 300 °C. Above an onset temperature of approximately 350 °C, partial decomposition of surface molecules occurs, characterised by progressive detachment of the terminating methoxy groups. In contrast, the spirobifluorene and phenylamine backbones retain structural integrity up to 500 °C, without evidence of evaporation or fragmentation, even for vacuum-deposited films. The loss of methoxy groups leads to a modification of the valence band structure, with the valence band maximum shifting towards higher binding energy and the ionisation potential increasing accordingly. These results define intrinsic thermal limits for pristine Spiro-OMeTAD and indicate that, provided other functional layers permit, processing temperatures up to 300 °C may be accessible, whereas exposure above 350 °C is expected to compromise interfacial electronic properties in PSCs.