Revealing Donor–Acceptor Interaction on the Printed Active Layer Morphology and the Formation Kinetics for Nonfullerene Organic Solar Cells at Ambient Conditions

Abstract

Slot‐die coating is a powerful method for upscaling the production of organic solar cells (OSCs) with low energy consumption print processes at ambient conditions. Herein, chlorobenzene (CB) and chloroform (CF) are compared as host solvents for printing films of the neat novel fused‐ring unit based wide‐bandgap donor polymer (PDTBT2T‐FTBDT), the small molecule nonfullerene acceptor based on a fused ring with a benzothiadiazole core (BTP‐4F) as well as the respective PDTBT2T‐FTBDT:BTP‐4F blend films at room temperature in air. Using CF printing of the PDTBT2T‐FTBDT:BTP‐4F active layer, OSCs with a high power conversion efficiency of up to 13.2% are reached in ambient conditions. In comparison to CB printed blend films, the active layer printed out of CF has a superior morphology, a smoother film surface and a more pronounced face‐on orientation of the crystallites, which altogether result in an enhanced exciton dissociation, a superior charge transport, and suppressed nonradiative charge carrier recombination. Based on in situ studies of the slot‐die coating process of PDTBT2T‐FTBDT, BTP‐4F, and PDTBT2T‐FTBDT:BTP‐4F films, the details of the film formation kinetics are clarified, which cause the superior behavior for CF compared to CB printing due to balancing the aggregation and crystallization of donor and acceptor.

Spectroelectrochemically determined energy levels of PM6:Y6 blends and their relevance to solar cell performance

“…In this way morphology tuning of the BHJ active layers by annealing can be documented and modified towards increasing the performance of the final device. 63,64…”

“…In this way morphology tuning of the BHJ active layers by annealing can be documented and modified towards increasing the performance of the final device. 63,64 Regarding the characterization of blend films our approach offers an additional advantage. The characteristic spectral response of each material allows us to discriminate between the two components in the blend and identify their individual contributions to the result.…”

Realizing the efficiency-stability balance for all-polymer photovoltaic blends

“…To further confirm this issue a morphology study, using grazing incidence wide-angle X-ray scattering (GIWAXS) measurement was undertaken. [58][59][60][61][62][63] Fig. 2(a) and (b) show 2D patterns of the binary PM6:PY-IT, and the PM6-b-PY-IT (one-pot produced films), whereas the fitted intensity profiles along the out-of-plane (OOP) and in-plane (IP) directions are shown in Fig.…”

Tuning the Crystallinity and Phase Separation by Two‐Step Annealing Enables Block Copolymer‐Based Organic Solar Cells with 15% Efficiency

“…To understand the enhancement of device performance, and device physics index, we performed a series of morphology characterizations, that is, grazing-incidence wide-angle and small-angle X-Ray scattering (GIWAXS & GISAXS) experiments, to quantitatively understand the change. [46][47][48][49][50] The 2D GIWAXS patterns of films are listed in Figure 3a, and in-plane (IP) and out-of-plane (OOP) directional linecuts are respectively plotted in Figure 3b,c. Likewise, the calculated parameters including peak position, d-spacing, and crystalline coherence length (CCL) are summarized in Table S2 and S3 100) and ( 010) peaks significantly increase.…”