According to your diagram, and my basic knowledge on electronics,
I think you should considere that connecting directly the diode to you voltaage source will damage you DIODE, so you need to limit the current
A resistor will do that (calculate and connect it in series with the led)
for example
your diode can work at 3.5 volts @ 15mA then
voltage source 9V
(9-3.5)/0.015 = R = 366 ohms, but thi value it just in calculation, the nearest value is 330 or 680 ohm's
so you will need to take into account spending more current with 330 or make an array of resistors.