Quaternary Organic Solar Cells Enable Suppressed Energy Loss

Abstract

Multi‐component organic solar cells (OSCs) composing of more than two donor and acceptor materials have attracted increasing attention, due to the possibilities to further mitigate voltage loss (ΔVoc) for the gain of open‐circuit voltage (Voc). However, the control of phase morphology in multi‐component blend systems that critically impacts ΔVoc and the ultimate power conversion efficiency (PCE) is still a challenge. Here, we report a quaternary blend‐based strategy for non‐fullerene OSCs by using two polymer donors (PM6 and L20) along with acceptors of a non‐fullerene (Y6) and PC71BM, leading to concurrent improvements of the Voc, device fill factor and eventual PCE. The quaternary OSC exhibits the advantages of a higher charge collection efficiency, expedited charge carrier sweep‐out, and reduced charge recombination losses. The suppression on ΔVoc is attributed to the reduced radiative recombination loss below the bandgap (0.143 V) and non‐radiative voltage loss (0.216 V). These properties are linked to synergies of modified energetics and film morphology of the quaternary blends. This work demonstrates that incorporating suitable donor and acceptor guest molecules to organic binary blend systems is a highly viable approach for lowering the energy loss in organic bulk heterojunctions towards the boost of photovoltaic performance for realistic energy conversion applications.

1,8,9‐Trihydroxyanthracene as a Green Solid Additive for Operational Stability in Organic Solar Cells

“…As shown in Figure , obvious fiber distribution was clearly seen in the blend films, which has previously been proved to be beneficial to exciton dissociation and charge transport in OSCs. [ 23,24 ] In detail, the reference D18‐Cl:N3 blend film showed a root mean square (RMS) value of 0.88 nm. The BHJ blend DPE‐treated D18‐Cl:N3 showed a larger RMS of 1.15 nm.…”

Finely Tuned Molecular Packing Realized by a New Rhodanine-Based Acceptor Enabling Excellent Additive-Free Small- and Large-Area Organic Photovoltaic Devices Approaching 19 and 12.20% Efficiencies

“…Compared to ternary blend OSCs, quaternary blend OSCs may serve different functionalities to improve the photovoltaic parameters and mitigate the trade-offs between these parameters. , Unfortunately, due to the existence of many components whose interactions with one another’s photophysical and opto-electronic properties can negatively affect a device’s performance, fabricating efficient quaternary blend devices is frequently difficult. With the exception of a few examples, this might explain the rarity of the reported achievements in quaternary small- and large-area OPVs. ,− In addition, the NFAs are generally advanced in terms of good miscibility, suitable energy levels, complementary absorptions, and compatibility with the host active layers . Thus, they might play a crucial role in optimizing the molecular packing morphology and good inter/intramolecular charge transfer (ICT) and hence approach the intrinsic best PCEs of NFA-based OSCs if appropriately applied as a guest component.…”

“…In addition, a multicomponent (quaternary) strategy, where a guest component is introduced into the ternary OSC systems, is an efficient way to improve the PCEs of small- and large-area OPVs. ,− A quaternary blend strategy can improve the film morphology, absorption properties, and good energy level alignment (e.g., by forming a small energy offset) for the active layer compared to ternary strategies. Thus, a feasible quaternary device has better balance of charge transport between the two carriers and reducing charge trapping.…”

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

“…[19] However, the fabrication of highly efficient quaternary co-blended systems is more challenging due to the increase in active layer components, in which the complex interplay between optical, photophysical, and electronic properties may actually lead to reduced device performance. [20] LBL-type OSCs might be more suitable for large-area fabrications by roll-to-roll method because they can offer precise control and improve device reproducibility. It has been the goal in the LBL-processed OSCs to obtain an ideal vertical morphology of the active layer to improve both charge generation and charge extraction.…”

“…[ 19 ] However, the fabrication of highly efficient quaternary co‐blended systems is more challenging due to the increase in active layer components, in which the complex interplay between optical, photophysical, and electronic properties may actually lead to reduced device performance. [ 20 ]…”