Asymmetric electron acceptor enables highly luminescent organic solar cells with certified efficiency over 18%

Abstract

Enhancing the luminescence property without sacrificing the charge collection is one key to high-performance organic solar cells (OSCs), while limited by the severe non-radiative charge recombination. Here, we demonstrate efficient OSCs with high luminescence via the design and synthesis of an asymmetric non-fullerene acceptor, BO-5Cl. Blending BO-5Cl with the PM6 donor leads to a record-high electroluminescence external quantum efficiency of 0.1%, which results in a low non-radiative voltage loss of 0.178 eV and a power conversion efficiency (PCE) over 15%. Importantly, incorporating BO-5Cl as the third component into a widely-studied donor:acceptor (D:A) blend, PM6:BO-4Cl, allows device displaying a high certified PCE of 18.2%. Our joint experimental and theoretical studies unveil that more diverse D:A interfacial conformations formed by asymmetric acceptor induce optimized blend interfacial energetics, which contributes to the improved device performance via balancing charge generation and recombination.

Achieving and Understanding of Highly Efficient Ternary Organic Photovoltaics: From Morphology and Energy Loss to Working Mechanism

“…Then to uncover why above mentioned asymmetric NFA attached with one indanone terminal and one cyano indanone (IC) terminal can be the material showing low‐energy‐loss and high‐efficiency, an asymmetric NFA of BO‐5Cl was synthesized and studied by Chen et al. [ 86 ] Single crystal structure reveals that BO‐5Cl with large dipole moment can stack more accurately with indanone terminal contacts with benzothiadiazole, thus leaving IC terminals stack together, while symmetric BO‐4Cl shows less packing modes (Figure 4d). Such molecular arrangement of BO‐5Cl brings benefits, including longer exciton lifetime, stronger hybridization between CT and local‐exciton (LE) states and the existing of a dual interfacial electronic manifold, which should be responsible for the highly luminescence property of BO‐5Cl.…”

“…Reproduced with permission. [ 86 ] Copyright 2022, Springer Nature. c) Theoretical calculation of molecular packing between NFAs.…”

“…b) Theoretical calculation of D:A complex configuration and state energies, and temperature-dependent EL spectra. Reproduced with permission [86]. Copyright 2022, Springer Nature.…”

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

“…[1][2][3][4][5][6][7][8][9][10][11][12] However, even though the record power conversion efficiency (PCE) has been pushed to a high level for both single-junction and tandem devices by researchers, its stability still causes the ''short board effect'', reducing users' confidence in this technology's commercialization prospects. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Therefore, the urgent issue to be solved, is the stability, or achieving the performance-stability balance for OSCs.…”

Controlling the Treatment Time for Ideal Morphology towards Efficient Organic Solar Cells

“…Organic solar cell (OSC) technology is one of the most promising photovoltaics (PVs) to be commercialized, which can address the energy consumption issue without causing carbon oxide emission, eventually contributing to carbon neutralization [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. To date, the urgent task for OSC researchers is to improve the power conversion efficiency (PCE) to a more competitive level, though it has been widely reported with > 18% [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]; the inputs of chemistry design/synthesis or ternary blend construction are unavoidable, yet the field demands a simple and effective way to improve the device efficiency based on mature material systems.…”