Fresh cucumber peels do work to keep roaches away.
However when you do put cucumber peels and other food sources near where the roaches are they will actually be more attracted to the area.
In reality to keep roaches away you want to make sure you keep food away from the roaches.
Put all food up, clean your countertops, make sure no food is on the counter etc.
Sweep up any crumbs, wipe the counter down etc and the roaches will usually stay away.
However if you do want to kill roaches with cucumbers make sure to poison the cucumbers with roach poison otherwise the cucumber peels will not kill the roaches.
You would really just be providing a food source to the roaches which will attract more roaches.
You can also use sticky pads to get rid of roaches, use roach motels and even use Borax to kill the roaches.
Make sure to sweep up any dead roaches or vacuum the dead roaches up when they die.
If you have a really bad roach problem you should hire an exterminator who can kill off all the roaches.
Or use a roach fogger to kill the roaches in your home by fogging them out with poison.