An apparatus includes a flexible silicon (Si) substrate, such as a crystalline n-type substrate, and a heterostructure structure formed on the silicon substrate. The heterojunction structure includes a first layered structured deposited on a first side of the silicon substrate. The first layered structured includes a first amorphous intrinsic silicon layer, an amorphous n-type or p-type silicon layer, and a transparent conductive layer. The second layered structure includes a second amorphous intrinsic silicon layer, an amorphous p-type or n-type silicon layer, and a transparent conductive layer. The heterostructure structure is configured to operate as a photovoltaic cell and an infrared light emitting diode.