"An IR QDSC would work in the six month Arctic winter due to the 43% of available light energy falling on earth which is IR."

The 43% of the available light (electromagnetic radiation) falling to earth as IR comes from the sun. When the sun goes below the horizon, the level of IR does not remain at 43% of the daytime sunlight level, it is dramatically reduced just like the level of visible light.

Yes, the earth and objects on it will heat up during daylight due to IR absorption and then when the sun goes down, the earth and the objects will re-radiate IR as they cool down, but this level of IR greatly reduce from day time IR levels.

So IR capable QDSCs will be able to generate some electricity at night, but the biggest contribution of IR capable QDSCs will occur during the day, if they are able to convert not just the IR light but also the visible light. By converting both the IR and visible light falling on a solar panel, you will produce more electricity for the given area. You don't waste the IR energy, like you do with a visible light only solar panel.

An added bonus is that IR is better a penetrating clouds so on cloudy days when the contribution from visible light significantly drops off, the IR contribution will experience less of a drop off in power production.