I want to grow moss or something green in-between pavers, in the sun

I love that idea. It's going to look great!

http://homeguides.sfgate.com/grow-moss-between-pavers-24969.html

I've done this and love it! Though my first time doing it, I put grass inbetween and it looked great, but was a pain to keep cut. The moss works great, and I now have put creeping jenny near the sides of the walkway, and love the way it flows over. Creeping thyme would also be good. There are many choices, and whatever you do will be really fun!

I'm planning on doing this someday! Our plan is to use sedum groundcover. There are a lot of different kinds to choose from, but they seems to thrive in less-than-ideal conditions in cracks and through droughts. Here's more info: http://www.finegardening.com/creeping-sedums

Have you tried spraying with buttermilk?

vinca or primrose