Photodetectors come in a wide variety of constructions and materials, with the Cu2O-based photodetector that [Mad Scientist Creations] demonstrates in a recent video being a good example of a photodetector that can be created at home using nothing but some copper and a heat source.
Of the two copper elements in a salt water cell, one element is heated to the point where a copper oxide layer forms, specifically Cu2O, which acts as a semiconductor and provides the photosensitive layer. Even a fairly crude sensor created with a regular gas stove produces enough of a current that it can be used in a simple light detection circuit.
Although copper-oxide photodetectors may seem quaint, they are getting a lot of interest as they feature a very narrow bandgap at 1.2 eV. In a 2019 study by [Hyeon-Joo Song] et al. as published inย Scientific Reports such a sensor is enhanced with an optimized grain structure that improves its performance, with much higher sensitivity and faster response times.
As demonstrated by [Andrzej Kwiatkowski] et al. in a 2024 paper inย Solar Energy Materials and Solar Cells these copper-oxide sensors can also be used for gas detectors, though they used advanced gas deposition to produce the thin films instead of sticking a bit of copper tape into a natural gas flame.
Even if DIY copper-oxide sensors aren’t quite as exciting as what one can do with access to a well-equipped (semiconductor) lab, it’s still a pretty accessible material that lends itself for easy experimentation.
Cool project. I’ve noticed that this YouTube channel is full of similar interesting little projects. I’m pretty sure this will inspire many youngsters to try some of them out.
Back in the 80s or 90s, Lindsey Electronics books had a pamphlet about this. Same process as far as I remember, billed as make your own solar cell.
This is old. Like 80+ years old.
https://royalsocietypublishing.org/rspa/article/171/946/281/5916/Note-on-copper-cuprous-oxide-photocells
or even older: https://technica.inc/cleantech/dailycleantech-hallwachs/
Fun experiment, and well worth doing, but if you are serious then take it to the next level and use low temperature electrochemical methods.
1. SUBSTRATE: Cu FOIL CLEANING & SCALE STRIPPING
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2. P-ABSORBER: POTENTIOSTATIC CuโO ELECTRODEPOSITION
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3. N-WINDOW: CBD ZnO DEPOT & ANNEAL
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4. CONTACTS: Ag FINGER GRID & WIRE ISOLATION
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