Realizing 19.05% Efficiency Polymer Solar Cells by Progressively Improving Charge Extraction and Suppressing Charge Recombination Abstract Improving charge extraction and suppressing charge recombination are critically important to minimize the loss of absorbed photons and improve the device performance of polymer solar cells (PSCs). In this work, highly efficient PSCs are demonstrated by progressively improving the charge extraction and suppressing the charge recombination through the combinat...