Aqueous-Processed Polymer/Nanocrystal Hybrid Solar Cells with Double-Side Bulk Heterojunction

Aqueous-solution-processed solar cells (ASCs) are promising candidates of the next-generation large-area, low-cost, and flexible photovoltaic conversion equipment because of their unique environmental friendly property. Aqueous-solution-processed polymer/nanocrystals (NCs) hybrid solar cells (AHSCs) can effectively integrate the advantages of the polymer (e.g., flexibility and lightweight) and the inorganic NCs (e.g., high mobility and broad absorption), and therefore be considered as an ideal system to further improve the performance of ASCs. In this work, double-side bulk heterojunction (BHJ), in which one BHJ combines the active material with electron transport material and the other combines the active material with hole transport material, is developed in the AHSCs. Through comparing with the single-side BHJ device, promoted carrier extraction, enhanced internal quantum efficiency, extended width of the depletion region, and prolonged carrier lifetime are achieved in double-side BHJ devices. As a result, power conversion efficiency exceeding 6% is obtained, which breaks the bottleneck efficiency around approximate to 5.5%. This work demonstrates a device architecture which is more remarkable compared with the traditional only donor-acceptor blended BHJ. Under conservative estimation, it provides instructive architecture not only in the ASCs, but also in the organic solar cells (SCs), quantum dot SCs, and perovskite SCs.