Over 30% transparency large area inverted organic solar array by spray

We report the fabrication and characterization of large scale inverted organic solar array fabricated by all-spray process. The inverted polymer solar cell geometry consists of four layers, in the order of ITO-Cs₂CO₃-(P3HT:PCBM)-modified PEDPT:PSS, on a glass substrate. With semitransparent PEDPT:PSS as anode, the encapsulated solar array shows more than 30% transmission in the visible-near IR range. Optimization of device is done by thermal annealing, and the optimal annealing conditions are shown to be different in single-cell test device and the multiple-cell array. Solar illumination has been demonstrated to improve solar array efficiency up to 250%. Device efficiency of 1.80% was observed with the array under AM1.5 irradiance. Our preliminary data have shown that the performance enhancement under illumination only happens with sprayed devices, not devices made by spin coating. This means that solar cells made with our spray-on technique performs better under sunlight, which is beneficial for solar energy application.