There are certain tricks they use like add more white to the screen to make it appear brighter, and If you're already at 100% monitor brightness and need more, I would mess around with the control panel(NVIDIA possibly)- Brightness and Contrast. You need both of them in order to make it look brighter yet still look clean.
By just adjusting ONLY the brightness your screen will become really white and look bad, which is why you need the contrast as well. Best way is to mess with it and see what suits you best.
Be careful not to put brightness all the way to 0 because it can be very hard to change it back, as your screen will go completely black.
Your monitor cannot be overclocked on brightness though so if it's 100% brightness already, I'd say your best bet is to do what I've mentioned above.
Hope this helps