Manipulating Charge Transfer and Transport via Intermediary Electron Acceptor Channels Enables 19.3% Efficiency Organic Photovoltaics

Abstract

Y-serious acceptors and the multi-components strategy, the power conversion efficiencies (PCEs) of the single-junction OPVs have already reached 19%, [19,20] with the best fill factors (FFs) exceeding 80%. [21,22] However, the trade-off between the open-circuit voltage (V oc ) and the short-circuit current density (J sc ) still remains as a challenge to handle with in OPV devices. [23][24][25][26][27] Therefore, the synergistic improvement of V oc and J sc will be attractive for marching the efficiencies further for OPVs. [28][29][30] The charge transfer (CT) state cannot only affect the energy loss (E loss ) but also the generation efficiency of photo-induced carriers. [26] Narrowing the offset (ΔE LE-CT ) between the energy level of the CT state (E CT ) and the lowest excited state (E LE ) may reduce the probability of excitons quenching back to the ground state, which helps in mitigating E loss for a higher V oc . However, the diminished driving force is not in favor of exciton dissociation for a higher J sc , and vice versa. [29] The properties of CT states at the donor-acceptor (D-A) interfaces are supposed to be affected by the morphology Balancing and improving the open-circuit voltage (V oc ) and short-circuit current density (J sc ) synergistically has always been the critical point for organic photovoltaics (OPVs) to achieve high efficiencies. Here, this work adopts a ternary strategy to regulate the trade-off between V oc and J sc by combining the symmetric-asymmetric non-fullerene acceptors that differ at terminals and alkyl side chains to build the ternary OPV (TOPV). It is noticed that the reduced energy disorder and the enhanced luminescence efficiency of TOPV enable a mitigated energy loss and a higher V oc . Meanwhile, the third component, which is distributed at the host donor-acceptor interface, acts as the charge transport channel. The prolonged exciton lifetime, the boosted charge mobility, and the depressed charge recombination promote the TOPV to obtain an improved J sc . Finally, with synergistically improved V oc and J sc , the TOPV delivers an optimal efficiency of 19.26% (certified as 19.12%), representing one of the highest values reported so far.

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

“…Since 2019, Y6 derivatives (especially for symmetric molecules) have become a hot topic of study in OPVs due to their excellent properties such as low band gaps and high electron mobility. , In addition to the symmetrical nonfullerene acceptors, asymmetrical nonfullerene (ANF) acceptors have recently been used successfully in OPVs. − In general, ANF acceptors are classified as asymmetry skeleton type nonfullerenes (ASNFs, A–D 1 A′D 2 –A) and asymmetry terminal type nonfullerenes (ATNFs, A 1 –DA′D–A 2 ) acceptors. Very recently, ternary OPV devices using the ATNF acceptor as the third component had excellent PCEs of over 19%. , However, an ASNF acceptor as the third component has never been studied or reported.…”

“…Very recently, ternary OPV devices using the ATNF acceptor as the third component had excellent PCEs of over 19%. 33,34 However, an ASNF acceptor as the third component has never been studied or reported.…”

Multiphase Morphology with Enhanced Carrier Lifetime via Quaternary Strategy Enables High‐Efficiency, Thick‐Film, and Large‐Area Organic Photovoltaics

“…In addition, BTP-S10 and L8-BO will form the parallel-like phase morphology when mixed with PM6 (ω BTP-S10 is −0.88 for PM6:L8-BO:BTP-S10 blend), which was also confirmed in our previous work. [46] So, the multiphase morphology could be realized in this quaternary blend.…”

Highly efficient and stable binary all-polymer solar cells enabled by sequential deposition processing tuned microstructures

“…[1][2][3][4][5][6] In the past few decades, researchers put tremendous effort into pursuing high power conversion efficiency (PCE) for OSCs, and as a consequence values 419% have been reported by many different groups. [7][8][9][10][11][12][13][14][15][16][17] However, the fruitful development solely of efficiency enhancement cannot fulfill the requirement of commercialized photovoltaic (PV) cargo, where the device stability matters equally importantly. [18][19][20] Due to the intrinsic disadvantages of small molecules in morphology stability, OSC devices with superior stability are more feasible when they contain an active layer with both polymeric donor(s) and acceptor(s).…”