I recently “discovered” solar LED driver ICs, such as the QX5252 and YX805. They are mainly designed to drive LED lights from a low-voltage rechargeable battery, with solar powered charging.
A core function is a boost converter circuit (similar to a joule thief) that allows LEDs with a forward voltage of over 2V to be driven from a 0.9V-1.5V battery.
As a test and demonstration, I’m ignoring the solar charging aspect here, and using the chip to drive an LED from a 1.55V coin cell. It just needs an external inductor to work.
Here’s a quick demo: