THE PROJECT OBJECTIVE IS TO DESIGN, PROTOTYPE, AND DEMONSTRATE AN ENTIRELY UNIQUE SOLAR CELL ARCHITECTURE WHICH COMPOSITES PEROVSKITE LAYERS WITH POLYMERIC NANOFIBERS THAT: (1) PROVIDE MECHANICAL REINFORCEMENT TO INCREASE THE COHESIVE FRACTURE RESISTANCE (GC) ~10-FOLD TO = 5 J M-2; (2) MITIGATE THE DIFFUSION OF MOISTURE ACROSS THE DEVICE AND INTO THE MOISTURE-SENSITIVE PEROVSKITE TO INCREASE THE RETENTION OF POWER CONVERSION EFFICIENCY (PCE) UNDER ACCELERATED AGING BY 50%, WITH INITIAL PCES OF AT LEAST 15%; AND (3) SWELL WITH MOISTURE EXPOSURE TO IMPART A COMPRESSIVE STRESS ON THE PEROVSKITE AND REDUCE THE INTERNAL TENSILE STRESSES OF PEROVSKITE TO BELOW 20 MPA.