High-Performance Pseudo-Bilayer Organic Solar Cells Enabled by Sequential Deposition of D18/Y6 Chloroform Solution

Recently, sequential deposition (SD) fabricated pseudo-bilayer organic solar cells (OSCs) have achieved preferable performances compared to the long-term adopted bulk hetero-junction (BHJ)-based devices, in which the solution-processing technique is the key to preparing the active layer of electron- donor materials and electron-acceptor materials. For devices with D18 as the electron-donor material and Y-serial small molecules as the electron-acceptor materials, however, one single solvent was seldom applied to prepare the corresponding high-perform-ance SD OSCs. In this work, we adopted chloroform as the single solvent and successfully constructed high-performance SD OSCs based on D18 and Y6. Benefiting from the finely adjusting of the vertical phase distribution, the SD low molecular weight D18/Y6 pseudo-bilayer device realized high short-circuit current density (27.24 mA cm-2) and a champion efficiency of 17.94%, which surpassed the 17.36% value of the D18:Y16 device having a bulk heterojunction structure and the 7.81% result of the SD prepared Y6/D18-based device. This work demonstrates a single solvent strategy for fulfilling high-performance SD OSCs and reveals the reasons that account for the distinct performances of these OSCs fabricated by different approaches.

Automated summary

Recently, high-performance pseudo-bilayer organic solar cells (OSCs) based on sequential deposition (SD) have been successfully fabricated using chloroform as a single solvent. These SD OSCs exhibit improved performance compared to the traditional bulk heterojunction (BHJ)-based devices. By finely adjusting the vertical phase distribution, the SD D18/Y6 pseudo-bilayer device achieved a champion efficiency of 17.94% and a high short-circuit current density of 27.24 mA cm-2, outperforming other devices with different structures and preparation methods.