A Novel Doping Layer Strategy to Realize High Efficiency Laye-by-Layer Organic Solar Cells

Abstract

Molecular doping is an effective mean to achieve high performance organic solar cells (OSCs). However, the introduction of dopants aggravates the problem of morphological complexity in bulk heterojunction (BHJ) OSCs, and the choice of solvent after mixing with the donor and acceptor is greatly limited. Here, we innovatively propose a solution to solve the above problems by inserting a dopant layer between the donor layer and the acceptor layer to construct OSCs with a stacked structure through layer-by-layer (LbL) spin-coating solution method. Compared with the control devices (16.95%), the performance of PM6/PABA/BO-4Cl devices with the addition of the dopant layer 4-Aminobenzoic acid (PABA) was significantly enhanced, achieving an efficiency of 17.46%. Morphological characterization and charge analysis showed that the performance improvement was attribute to the film morphology optimization by the dopant located at the D/A interface, while effectively increasing the exciton dissociation rate and charge mobility of OSCs. Thus, our work demonstrates that the doping layer strategy coupled with sequential solution deposition is an effective way to construct efficient devices and is a promising alternative to BHJ OSCs.