Electronic – Switching bjt transistor with photodiode

Important notice This is an IR diode: Daylight blocking filter matched with 870 nm to 950 nm emitters. IR photodiodes usually have an opaque black package, while visible light photodiodes are in clear packages. You could look for a photodiode (a phototransistor is even more sensitive) with an eye sensitivity curve. I remember having used the SFH3410 from Osram here.

Then the good news: a photodiode or phototransistor acts as a current source, so a series resistor is sufficient to convert the current to a voltage. In your datasheet the graph of figure 3 is the one you need. The reverse current varies between 1uA and 100\$\mu\$A. A series resistor of 10k converts this to 10mV - 1V. You could increase this to get a higher voltage, you'll have to experiment with light levels and resistor value to achieve a full range of 5V. Also keep in mind that the input impedance of the ADC is parallel to the measurement resistor, reducing sensitivity.

The graphs below are from the SFH3410's datasheet. If you keep in mind that you need a \$V_{CE}\$ of at least 0.5V (right graph), you'll be limited to 4.5V output from a 5V power supply.

Further reading:
SFH3410 application note

How can I increasy sensitivity of the photodiode

Sensitivity is usually not really a function of the photodiode but of the receiver circuit after the photodiode. One effect of the photodiode itself is that using a smaller photodiode will reduce its capacitance which might allow you to use a more sensitive receiver circuit.

Note: Sensitivity means the smallest signal an optical receiver can detect. Responsivity is photodiode characteristic giving the ratio between the optical input power and electrical output current.

If you meant to ask about responsivity, for a photodiode, it's typically limited to 1 electron produced per photon received, so there is a maximum limit and you'll find many photodiodes approach this limit very closely. If you really need higher responsivity, you can consider using an avalanche photodiode but this requires a high-voltage driver circuit which is much more complex than what you have now.

(and possibly reduce effect of daylight)?

You can add an optical filter in front of the photodiode to pass through your laser wavelength and block other wavelengths.

Another typical trick is to modulate the laser at some frequency (often 40 kHz) and then add an electronic filter after the photodiode to specifically detect those signals. Off the shelf "IR" transmitters and receivers (like for the remote control of your TV) typically include the 40 kHz modulation and demodulation circuits.