Multi‐Functional Solid Additive Induced Favorable Vertical Phase Separation and Ordered Molecular Packing for Highly Efficient Layer‐by‐Layer Organic Solar Cells

Abstract

Layer‐by‐layer (LBL) deposition strategy enabling favorable vertical phase distributions has been regarded as promising candidates for constructing high‐efficient organic photovoltaic (OPV) cells. However, solid additives with the merits of good stability and reproducibility have been rarely used to fine‐tune the morphology of the LBL films for improved efficiency and stability. Herein, hierarchical morphology control in LBL OPV is achieved via a dual functional solid additive. Series of LBL devices are fabricated by introducing the solid additive individually or simultaneously to the donor or acceptor layer to clarify the functions of additives. Additive in the donor layer can facilitate the formation of preferable vertical component distribution, and that in the acceptor layer will enhance the molecular crystallinity for better charge transport properties. The optimized morphology ultimately contributed to high PCEs of 16.4% and 17.4% in the binary and quaternary LBL devices. This reported method provides an alternative way to controllably manipulate the morphology of LBL OPV cells.

Achieving 15.81% and 15.29% efficiency of all-polymer solar cells based on layer-by-layer and bulk heterojunction structures

“…The exciton dissociation efficiency (h D ) and charge collection efficiency (h C ) can be evaluated according to J * ph /J sat and J & ph / J sat , respectively, as shown in Table S1 †. [29][30][31][32] The h D values of all-PSCs without or with CN are 92.92% or 94.61% for the BHJ structure, 92.66% or 94.43% for the LbL structure. The larger h D for the BHJ all-PSCs should be mainly attributed to more PM6:PY-IT interfaces in the BHJ active layers.…”

Efficient semi-transparent organic solar cells enabled by a quasi-heterojunction active layer structure

“…25–27 A quasi-heterojunction of a SD-type active layer has desired vertical component distribution of the donor and acceptor, which is beneficial to charge collection. 28,29 More recently, the PCE of SD-type OSCs has been reported to be over 18%, which is comparable to the results of BHJ-type OSCs. 6,30 The SD method also demonstrated great potential for ST-OSCs.…”

Highly Efficient Layer‐by‐Layer Processed Quaternary Organic Solar Cells with Improved Charge Transport and Reduced Energy Loss

“…The surface energy of the PM6/Y6 and PM6:PM7/Y6:O1‐2F films is 37.14 and 37.59 mJ m −2 , respectively, which are close to the surface energy of pure acceptor films, indicating that the acceptors are enriched on the top surface, and a p–i–n structure that is favorable for charge collection is formed. [ 47 ] Besides, the miscibility between the donor and the acceptor can be estimated by the Flory–Huggins interaction parameter ( χ donor–acceptor ). [ 48,49 ] The value of χ donor–acceptor can be derived using the following empirical equation [ 50,51 ] where K is a positive constant, and the γ donor and γ acceptor are the surface energy of the donor and the acceptor.…”