Two volatile solid additives were developed to modulate the active-layer morphology of all-polymer solar cells (all-PSCs). Among them, the 4-BDBTP-treated all-PSC achieved an outstanding efficiency of 19.30%.
A new hybrid strategy synthesizes the TQT acceptor with thiadiazole and quinoxaline units. The resulting TQT-based OSC achieved 18.52% efficiency, topping linear trimer acceptor-based OSCs, while also exhibiting robust stability.
Recently, more attention has been paid to the heterocycles of perylenediimide-based small-molecule acceptors (SMAs) in aiming to improve the efficiency of the corresponding non-fullerene polymer solar cells (NF-PSCs). Meanwhile, recent studies have revealed that asymmetric configuration could provide better photovoltaic performances than its symmetric configuration. Herein, we design and synthesize the asymmetric and symmetric fused perylenediimide dimer (FPDI)-based small-molecule acceptors (FPDI-Se and FPDI-2Se) by incorporating the selenophene heterocycle into the bay position of FPDI. The effect of this Se heterocycle in the optical and electrochemical properties are systematically studied and discussed. Interestingly, with PTB7-Th as the polymer donor, the symmetric annulated acceptor FPDI-2Se-based device only gave an inferior power conversion efficiency (PCE) of 4.45% with a poor fill factor (FF) of 39.5%, whereas the asymmetric annulated acceptor FPDI-Se-based device, however, showed the remarkable enhanced PCE of 6.61% with an increased short-circuit current density of 14.78 mA/cm2 and an improved FF of 56.1% in NF-PSCs, which was attributed to the better intra- and intermolecular interactions of FPDI-Se compared with those of FPDI-2Se. These results indicate that the design and development of the heteroannulated-FPDI electron acceptors with asymmetrical configuration is an effective strategy by which to improve the photovoltaic performances of PSCs.
High-efficiency organic solar cells are often achieved using toxic halogenated solvents and additives that are constrained in organic solar cells industry. Therefore, it is important to develop materials or processing methods that enabled highly efficient organic solar cells processed by halogen free solvents. In this paper, we report an innovative processing method named auxiliary sequential deposition that enables 19%-efficiency organic solar cells processed by halogen free solvents. Our auxiliary sequential deposition method is different from the conventional blend casting or sequential deposition methods in that it involves an additional casting of dithieno[3,2-b:2',3'-d]thiophene between the sequential depositions of the donor (D18-Cl) and acceptor (L8-BO) layers. The auxiliary sequential deposition method enables dramatic performance enhancement from 15% to over 18% compared to the blend casting and sequential deposition methods. Furthermore, by incorporating a branched-chain-engineered acceptor called L8-BO-X, device performance can be boosted to over 19% due to increased intermolecular packing, representing top-tier values for green-solvent processed organic solar cells. Comprehensive morphological and time-resolved characterizations reveal that the superior blend morphology achieved through the auxiliary sequential deposition method promotes charge generation while simultaneously suppressing charge recombination. This research underscores the potential of the auxiliary sequential deposition method for fabricating highly efficient organic solar cells using environmentally friendly solvents.
Abstract Reduction of non‐radiative energy loss (Δ E nr ) in all‐polymer solar cells (all‐PSCs) is crucially important for achieving high power conversion efficiencies (PCEs). Herein, an efficient strategy is reported to reduce the Δ E nr by introducing luminescent unit into the backbone of polymer acceptors. Compared to the device based on PM6:PYDT, the Δ E nr in all‐PSC based on PM6:PYDT‐CzP‐9 has decreased from 0.188 to 0.183 eV. This reduction is attributed to the improvement in electroluminescence external quantum efficiency (EQE EL ). The PM6:PYDT‐CzP‐9 device has shown an 18% increase in EQE EL compared to the device based on PM6:PYDT (8.4 × 10 −4 vs 7.1 × 10 −4 ), demonstrating that the incorporation of luminescent unit in polymer acceptors is highly effective in enhancing the electroluminescence performance of all‐PSCs. As a result, the PM6:PYDT‐CzP‐9 device yielded a high V OC of 0.967 V, without the sacrifice of short‐circuit current density (23.42 mA cm −2 ) and fill factor (77.5%), leading to a high PCE of 17.55%.
A series of novel non-volatile DTC solid additives with a long flexible alkyl chain were designed and synthesized to improve the efficiency, photostability and mechanical durability of all-polymer solar cells (all-PSCs).
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