The integrated LED flash on your smartphone can improve your capture in low light, but apparently a constant light source is better such as the Pocket Spotlight.
This is a practical, portable light source that measures 2.5 x 1.5 inches. As we can see from the images, the pocket spotlight features ultra portable design, and comes with a built-in array of LED lights, and using removable 3.5 mm audio connector you can easily plug the spotlight on your smartphone or tablet in order to offer you a constant light source for low light event photography. Moreover, removing the audio connector, you can also attach it onto the hot-shoe of your camera. Apart from that, the portable spotlight is powered by built-in rechargeable battery that can offer up to an hour of brightly shining at full USB charge.
The pocket spotlight is priced at $30 USD ($40 for the spotlight with color filters). If you’re interested, jump to Photojojo online store for more details.