High‐Throughput Multiparametric Screening of Solution Processed Bulk Heterojunction Solar Cells

One of the major bottlenecks in the development of organic photovoltaics is the time needed to evaluate each material system. This time ranges from weeks to months if different variables such as blend composition, thickness, annealing, and additives are to be explored. In this study, the use of lateral gradients is proposed in order to evaluate the photovoltaic potential of a material system up to 50 times faster. A platform that combines blade coating using controllable velocity profiles (thickness gradients) with multichannel dispensers (composition gradients) and controlled lateral annealing variations (nanostructure gradients) is introduced. These samples are then analyzed using photocurrent and Raman imaging in order to correlate one to one the device performance, thickness, composition, and annealing temperature. The strength of the developed technology is shown by optimizing three different systems, namely PCDTBT:PC70BM, PTB7‐Th:PC70BM, and PffBT4T‐2OD:PC70BM, obtaining efficiencies ≈5%, 8%, and 9.5%, respectively, using less than 10 mg of each polymer in the process.
The authors are indebted to Dr. Bernhard Dörling for the development of the blade coating accelerating electronics, and Xavier Tejero and Prof. Alejandro Goñi for their help with setting up the LBIC system. The authors would also like to thank Dr. Juan Cabanillas (IMDEA) for useful discussions. The authors would like to acknowledge financial support from the Ministerio de Economía y Competitividad of Spain through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV‐2015‐0496) and project MAT2015‐70850‐P; and the European Research Council (ERC) under grant agreement No. 648901.