I am using PNG image but its size is getting too big so I have to compromise with its quality. So i was thinking vectors may be the another way around ?
Example will be a great help.
Can we use VectorDrawable or VectorXML as icons for push notifications?
Yes, just call the vector drawable the standard way for notifications:
In order to use the transparency (notification icons are only white and/or transparent), you will have to use the alpha channels when settings the colors in the vector XML, meaning #00000000 for transparent and #FFFFFFFF for white.