Creating an IR sensor
What you propose will work as long as you can keep all other light out of the sensor.  If the sensor is inside some equipment where it will always be dark except your transmitted IR, then you may get away with it.  Even then, varying temperature will add a varying DC offset to your received signal.  AC coupling the signal from the sensor and using a protocol that doesn't depend on the DC level is a good idea.

In most cases though, the ambient light level is unknown but can easily vary be several orders of magnitude during normal operation.  It can also be stronger than the transmitted signal.  The way this is usually dealt with is to make sure the transmitted signal is modulated on a carrier.  The ambient level is close to a DC offset and can then be filtered out.

The common three-terminal IR receivers do several useful things all in one cheap integrated package.  They filter out frequencies outside the IR LED range (usually around 910 nm) that the sensor still responds to, do the amplification, DC rejection, carrier detection, and demodulation.  You supply 5V and ground, and the third pin indicates when it see the presence of IR modulated at the specific frequency for that device.  These devices are available at a range of frequencies in the 30-50 kHz range.  It may take up to 10 carrier cycles for this integrated receiver to indicate the presence of the carrier.

Common consumer devices, like TV remotes, use a protocol above this such that everything is encoded as bursts of carrier of varying lengths and varying gaps between bursts.  The information is carried in the length and sequence of the bursts and spaces.  There are various things that can go wrong with this process, so it's a good idea to send data in packets with a checksum in each packet.  If the direction is one way, then send everything mutliple times because no one packet is guaranteed to be received.

Now that you say these are PIR sensors:

PIR sensors are quite different from IR photosensors.  Basically, they are at opposite ends of the infrared spectrum.  IR photosensors are sensitive to just below visible light.  910 nm is a common center wavelength, for example.  PIR sensors are meant to detect the black body radiation from something like a human walking around the environment.  They work on a different principle than a photodiode or phototransistor, and are meant to pick up much longer wavelengths.

You have to decide what you are trying to do.  If you want to detect people moving around in a room, then a PIR sensor is appropriate with the right lens or occlusion.  If you want to do digital communication, then a PIR sensor is essentially useless and you want a IR photodiode or phototransistor.  This is what I thought you wanted (since you originally mentioned a emitter) when I wrote the original section of my answer above.