Layout flexibility for sheet-to-sheet produced flexible ITO-free organic solar modules with organic functional layers slot die coated under ambient atmospheric conditions
Four different module layouts for indium tin oxide (ITO)-free flexible organic solar modules with device performance varying from 1.8% to 2.7% are reported in this work. Module 1, with a device efficiency of 2.5% on an active area of 88 cm2, demonstrates the up scaling of small area cells to larger area modules. Module 2, with a device efficiency of 1.8% and 106.4 V on an active area of 32.6 cm2, demonstrates high voltage on a small area. Module 3, with a device efficiency of 2% on an active area of 60.8 cm2 with a hexagonal layout, demonstrates the flexibility in module layout. Module 4 built as a reference module device on small active area of 6.1 cm2 had a device efficiency of 2.7%. PEDOT:PSS together with a metal grid is the transparent hole contact replacing ITO. The reference modules were also built without the metal grid (only PEDOT:PSS has a hole contact) and measured under 2000 and 500 lx resulting in the modules without grid outperforming the ones with grid. Therefore for indoor applications modules can be processed even without the top metal grid for current collection which not only reduces the material cost and the number of processing step but also eliminates the major concern of depositing metal electrodes on top of organic layers.