Roll to Roll Flexible Microgroove based Photovoltaics

Roll to Roll Flexible Microgroove based Photovoltaics

John Topping
Big Solar

The concept and development of a non-horizontally integrated photovoltaic design is discussed that aims to produce low-cost, roll-to-roll solar cells. A roll-to-roll, 3D embossed architecture is examined that utilizes the internal geometry of embossed grooves. This allows for traditional top and bottom contacts to be made within the groove in the horizontal plane. Secondary groove patterns also allow for horizontal cell-to-cell and module-to-module electrical interconnections. This process is achieved via off axis vacuum deposition, and prepares the substrate for device completion via a suitable photoadsorber being applied to fill the groove. Cascades of grooves are linked in series to give a desired voltage multiplication, with series linked cascades connected in parallel for high current applications. Results of copped indium di-selenide (CuInSe2) based devices have shown how the voltage multiplication is achieved. This solution to 3D interconnections allows any photoabsorber to be used; with PbS, perovskite and P3HT/PCBM having all been used to fabricate devices. This demonstrates the ability for a low cost, roll-to-roll process that can produce PV at less than 7p per Watt.