Distance between nozzle and substrate has been identified as one of the process parameters in spray coating that had a
great impact on the morphology of deposited layer.
Many researches have been conducted to analyze and optimize the nozzle to substrate distance for the deposition of active layer.
Vak et al. [53] identified three different regions between airbrush nozzle and substrates,which are “wet”, “intermediate”, and “dry”.
They found that the best linear control over thickness as a function of spraying time was in the “intermediatezone”. Susanna et al. [48] observed the same phenomenon in which below 15 cm (distance between sample and airbrush) the deposed material remained wet while over 20 cm from the substrate,produced dry and powdery films.
The “intermediate” zone is at 17cm.
At this point the samples showed good uniformity with a maximum PCE of 4.1%.
Saitoh et al. [39] found that at 10 cm,an irregular and higher thickness film was formed, uniform thickness was formed at 20 cm distance while less uniformity and thickness were observed at 30 cm (nozzle to substrate distance).