I’m currently running a game where my players are at level 4. The Drow have come from the underdark and are trying to claim the land. After an encounter, the players left one alive for questioning. The following morning, they found that the sun was having an effect on the surviving Drow and so they now know about the sunlight Sensitivity. They’re looking for magical items or spells that can help them in further battles if the Drow Attack at night. Sun Blade seems like a good weapon for them to discover, I can write a quest for them to follow to find the blade at the end but I’m asking for advise on other magical items or spells. I know that daylight is no help to me as that is only bright light, not sunlight. I was considering creating some form or single use, sunlight giving gem that will last for 2-3 rounds of combat that they could place somewhere to give the Drow disadvantage but with the limit then it wouldn’t be too OP. Any thoughts would be greatly appreciated. Thanks, Luke. 

Curse of Strahd has a lot of sunlight items. They all have some lore built up around them, but can be rewritten. I would personally judge that Daylight does create sunlight. The description may only say "Bright light", but the name specifies that it is or is like sunlight. 

I'd be wary about giving out a Sun Blade; it'll trivialize any level-appropriate drow encounters unless they've fallen into a trap or are fighting overwhelming numbers. That makes sense for Curse of Strahd because Strahd is CR 15 and the players will spend most of the adventure below level 10. Something consumable is a lot less likely to cause problems.

What you are looking for is more along the lines of a Driftglobe.

Thanks everyone. Really appreciate your help. You’ve steered me clear of the Sun Blade. Having that will just make all of the Drow encounters far too easy. I’m looking into re-designing the driftglobe to have sunlight instead of bright light and to only last a few rounds of combat.