Alkoxy Substitution on Asymmetric Conjugated Molecule Enabling over 18% Efficiency in Ternary Organic Solar Cells by Reducing Nonradiative Voltage Loss

Abstract

A ternary strategy is considered to be an efficient and simple way to further enhance the performance of organic photovoltaics (OPVs). However, the “structure–performance” correlation of the third component in the ternary device has rarely been clearly understood from the aspect of the material’s eigenproperties. Herein, this relationship is investigated in depth by employing three asymmetric skeleton nonfullerene acceptors as the third component in the host system of PM6:BTP-eC9, respectively. Compared with TB-S and TB-S1, the alkoxy-substituted TB-S1-O possesses a more stable planar conformation, a higher surface energy, and a larger ordered stacking domain due to the existence of noncovalent conformational locking (O···H). Consequently, the PM6:BTP-eC9:TB-S1-O device exhibits the highest efficiency of 18.14% as compared with the devices based on PM6:BTP-eC9:TB-S (16.16%) and PM6:BTP-eC9:TB-S1 (16.18%). Most interestingly, only the PM6:BTP-eC9:TB-S1-O device can maintain the positive effect of V OC improvement, because a significant reduction in nonradiative voltage loss can be observed in this device. Our systematic study reveals that alkoxy substitution on an asymmetric backbone is an efficient method to construct the third component for high-performance ternary organic solar cells.

Balancing the Efficiency and Synthetic Accessibility of Organic Solar Cells with Isomeric Acceptor Engineering

“…It is further verified by a photoluminescence (PL, Figure S19, Supporting Information) study that the quenching efficiency of PM6 emission in the PM6:BTPm-4Cl films (96.3%) is higher than that of PM6:BTP-o-4Cl films (92.3%), which also means the easier and faster exciton dissociation for PM6:BTP-m-4Cl blended system. [24] The integrated J SC calculated by EQE curves of PM6:BTP-m-4Cl and PM6:BTP-o-4Cl based devices are 26.30 and 24.04 mA cm −2 , respectively, both of which are consistent with the values measured by solar simulator. Meanwhile, the uniform tendency of internal quantum efficiency (IQE) for the two systems in the range of 450-870 nm further verifies the higher photon to electron conversion efficiency in the PM6:BTP-m-4Cl devices (Figure S18b, Supporting Information).…”

Versatile Self‐Assembled Molecule Enables High‐Efficiency Wide‐Bandgap Perovskite Solar Cells and Organic Solar Cells

“…The PEDOT:PSS‐based control device prepared according to the reference was also constructed to achieve a best PCE of 17.93%, comparable to the published result in literature. [ 48 ] In contrast, the binary OSCs with BCBBr‐C4PA deliver over 18% PCEs with active layers prepared from a wide range of spin‐coating speed from 5000 to 8000 rpm. The maximum PCE can reach as high as 18.84%, accompanied by an significantly increased J SC (27.60 mA cm −2 ) and FF (79.30%)..…”

Selenium‐Based Nonfused Electron Acceptors for Efficient Organic Photovoltaic Cells

“…In addition, the nonradiative part Δ E nonrad determined by the equation of are 0.229, 0.249, 0.260, and 0.298 eV for ASe‐1‐, ASe‐2‐, ASe‐3‐, and A4T‐16‐based devices, respectively. [ 55 ] From these results, we can find that Se substitution could help reduce the of the OPV cells. According to the theory in the previous article, [ 56 ] as the Se‐substituted nfEAs have slightly upshifted HOMO levels compared to A4T‐16 (Figure 1f), the difference between the energy of the lowest singlet exciton state ( E S1 ) and the lowest charge transfer (CT) state ( E CT ) of the D–A blend becomes smaller.…”