Also, I can think of an excellent use of IR solar cells: turning heat into electricity. Wouldn't it be cool if you could always keep the heat in your house less than 75 degrees F, and produce electricity in the process, because your whole floor is a huge IR solar cell?
Because Silicon is similar to carbon, Silicon can do many of the things Carbon can. We know Silicon extremely, extremely well. We have been working out the kinks in it for 30 years, Intel has put billions of dollars into researching the material. We know how it works. Other materials fall off very quickly in our level of knowledge, we are still at the point in some of them that we know they work, but we don't know why. Carbon is getting a lot of attention, maybe because it's the next best step, or maybe because understanding Carbon will let us continue to push Silicon forward until years in the future when we have a better understanding of the material when we can transition nicely.
As for making heat -> You could, but the peak wavelength from the black body spectrum of the room would be about 10 microns. These solar cells are significantly shorter wavelength than that (they're absorbing ~1 micron radiation). Also, the longer the wavelength the less energy you get per photon, which wouldn't fare very well.
For heat to electricity, you need a TEG (thermoelectric generators, peltiers, something that uses the Seebeck effect) or a sterling engine of some kind. These work off temperature differentials. Unfortunately, thermodynamics is not nice about recouping energy, and they need high temperature differentials to function efficiently. Even then, the efficiency maxes at about 30% (Carnot efficiency for heat engines).
Near IR is generally up to 1400nm wavelength, where the infrared from heat isn't really a factor til you hit 4000nm.
The intensities of NIR are too low to be worthwhile.
The scientists made something that could see your remote control's LED, not your body heat.
It's a lot like the tiny paddlewheel attached to a ratchet Richard Feynman analyzed, you end up with an even dice roll 4/5 times you win but that 1/5 makes up for all those gains.
PS: Don't forget solar cells work because the sun is hot, and there is plenty of black body radiation to go around.
To make electricity the captured photons have to fall to a lower state - but if the solar cell is the same temperature the photons can't do that.