I need to detect room luminosity. I was thinking to use normal LED and op amp to bring the signal to PIC adc.
Will the selected op amp in the below circuit be OK?
A light-dependent-resistor would have a much greater sensitivity than a LED and would be easier to interface with the PIC. The opamp might not even be necessary. The 741 is a poor choice of opamp; much better ones are available (e.g. rail-to-rail types with negligible input offset).
The non-inverting input (pin 3) of any opamp MUST be connected to a DC reference voltage or the opamp will not work!
The 741 opamp is about 45 years old and has horrible spec's. It is designed to use only a 30V supply and most will not work from a supply that is only 5V.