Control of the Crystallization and Phase Separation Kinetics in Sequential Blade‐Coated Organic Solar Cells by Optimizing the Upper Layer Processing Solvent

Abstract

Sequential deposition of the active layer in organic solar cells (OSCs) is favorable to circumvent the existing drawbacks associated with controlling the microstructure in bulk‐heterojunction (BHJ) device fabrication. However, how the processing solvents impact on the morphology during sequential deposition processes is still poorly understood. Herein, high‐efficiency OSCs are fabricated by a sequential blade coating (SBC) through optimization of the morphology evolution process induced by processing solvents. It is demonstrated that the device performance is highly dependent on the processing solvent of the upper layer. In situ morphology characterizations reveal that an obvious liquid–solid phase separation can be identified during the chlorobenzene processing of the D18 layer, corresponding to larger phase separation. During chloroform (CF) processing of the D18 layer, a proper aggregation rate of Y6 and favorable intermixing of lower and upper layers results in the enhanced crystallinity of the acceptor. This facilitates efficient exciton dissociation and charge transport with an inhibited charge recombination in the D18/CF‐based devices, contributing to a superior performance of 17.23%. These results highlight the importance of the processing solvent for the upper layer in the SBC strategy and suggest the great potential of achieving optimized morphology and high‐efficiency OSCs using the SBC strategy.

Efficient Near-Infrared Organic Photodetectors with Spectral Response up to 1600 nm for Accurate Alcohol Concentration Detection

“…Interestingly, compared to BHJ film, a redshift of about 27 nm in the characteristic peak of COTIC-4F was observed in the hybrid p-PHJ/BHJ film. This subtle difference in the absorption spectra may be due to the introduction of N2200 resulting in the stacking of COTIC-4F, which can be evidenced by the enhancement of crystallinity in the subsequent grazing-incidence wide-angle X-ray scattering (GIWAXS) results. , Remarkably, hybrid p-PHJ/BHJ film shows enhanced absorption intensity at 300–1000 nm, suggesting that the construction of this hybrid p-PHJ/BHJ structure would be beneficial in enhancing the absorption of high-energy photons.…”

Unraveling High Reproducibility and Broad Composition Tolerance in High‐Efficiency Organic Solar Cells via Sequential Deposition

“…The slope of peak position in LBL film is slightly high, indicating a fast aggregation and crystallization process. [ 35 ] In the third stage, all the solvent evaporates and the film is formed. The signal of peak position and peak intensity become stable.…”

Advances in layer-by-layer processing for efficient and reliable organic solar cells

“…Ma and coworkers, evaluated the influence of processing solvents on the film morphology and device performance of D18/Y6-based LBL OSCs processed by blade coating under ambient conditions. 139 The device performance mostly relied on the choice of solvent to deposit the donor layer. When the D18 donor layer was processed from CF solution the device yielded an excellent PCE of 17.23%.…”