Hello Hickey,

I suggest searching for coating procedures resulting in particle monolayers.

As long as your contact line is pinned and the drop evaporates a flow and a particle transport are likely. Cleaning and plasma activation of the glas will reduce the contact angle --> the curvature and therefore the effect. Complete wetting by using a low tension liquid (for the dispersion of the particles) should prevent the effect (no (pinned) triple line). 

HELLO HICKEY, 

Adding a small amount of surfactant is best method to eliminate coffee ring effect . in my publication I have used this approach, and it is useful. Further-More if we do not want to use additives in the system, then we can use self-assembly for removing the ring formation. If the particles are photo-active than such as TiO2 ...than  UV light source will also be useful. Hope this will be useful for you.    

https://pubs.acs.org/doi/abs/10.1021/acs.jpcc.6b09519

I removed coffee stain using TiO2 nanoparticles, first you can use the detergent and later you can use the photocatalytic oxidation reaction to remove it

When otherwise inclined, you could test spin-coating the drop. This will push the boundary out (rather than trying to eliminate it from being pinned in a static experiment). The experimental balance becomes a trade off in forced spreading and evaporation as opposed to natural spreading/contracting and evaporation. The new "handle" to adjust for a proper coating is the spin-rate.

It depends what your solution is made of. But if you do not want (or cant) alter the chemistry of the solution, then your only option is to change the evaporation kinetics. You can try to dry faster at room temperature - but this may lead to mis-orientation or degradation of your molecules in solution (again not sure what you are trying to do). or you can try freeze drying. If you can freeze abruptly your solution on your substrate 9say with a plate at liquid N2 temperature) then you can easily use that in a freeze drier to sublimate the solution.

To add to what has been said already

Try to dry it faster at room temperature by flowing N2 gas or by applying vacuum. We can also think of high temperature drying if degradation of molecules it not an issue.

You can try other coating techniques such as dip coating, spray painting etc.