Unique ability of PX to polymerize from a gas phase on all surfaces and to cover them conformly is making the process very useful for devices with small functional units.
Low chemical reactivity of PX making it almost unavoidable material for multialyered organic thin film devices.
No solvent, no plasma, no temperature to damage the surface of underlayer.

But it is really one material for co-deposition with dye in a vacuum.
Publ. in Optical memory and Neural Network, 2004 (Shortened): Studies of PPX-C  film morphology and optical properties (Download PDF).
 

PPX-C by pyrolytic method with plasma activation at the beginning.

 
PPX-C by pyrolytic method with simultaneous plasma activation.