Since 

• I can cut-to-size any photovoltaic cell I desire,
• creating a MIPI circuit probably takes longer than a photovoltaic circuit,
• I'd need to source and/or make animation files for the screen and 
• the screen would reduce battery life instead of increase it, 

I'm thinking of focusing on the solar version going forward and, once I've got a Tetent that works, consider engineering an LCD backlit solution.

It might also be possible to find a reverse mode PDLC sheet and, coupled with LEDs on the edges of the acrylic / lexan window, allow the choice of absorbing ambient light energy or a solid white LED backlight. The reason for the inverse/reverse mode sheet is because normal PDLC film requires energy to become transparent. This is the kind of PDLC I need:

It seems that the name for this material is "PNLC film":