Naphthalene as a Thermal‐Annealing‐Free Volatile Solid Additive in Non‐Fullerene Polymer Solar Cells with Improved Performance and Reproducibility

Abstract

Highly volatile solid additives have attracted much attention recently because they enhance molecular packing order and possibly solve the problems of poor reproducibility and instability of polymer solar cells (PSCs) with solvent additives. The shortcoming is that existing solid additives require thermal annealing (TA) to remove them from the active layer, leading to an increase in the complexity of the device fabrication process and morphology rearrangement problems. This study introduces a commercially available, low-cost, and highly volatile material, naphthalene (NA), as a solid additive used in PSCs based on PM6: Y6. NA is well mixed with a non-fullerene acceptor and can restrict excessive aggregation of the donor and acceptor, producing efficiencies comparable to PSCs processed by 1-chloronaphthalene (CN) solvent additive. As a result, a maximum power conversion efficiency (PCE) of 16.52% for NA-processed PSC is achieved, higher than that of a PCE of 16.07% for CN-processed PSC with TA. NA-processed PSCs exhibit comparable efficiencies (PCE of 16.10%) without TA treatment and higher reproducibility/stability than CN-processed PSCs. This study demonstrates a low-cost and excellent volatile solid additive to improve the device performance and the potential for exploring new solid additives that can readily be made volatile without TA.

Dithienobenzoselenadiazole-Based Polymer Donors with Tuned Side Chains for Efficient Polymer Solar Cells

“…This implies that trap-assisted recombination in the PSe-HD-based device is more efficiently inhibited. 60 The relationship between J sc and P light can be described as J sc ∝ (P light ) α . The α values of the PSe-BO-and PSe-HD-based PSCs are 0.975 and 0.983, respectively, which imply that the PSe-HD-based device has less bimolecular recombination than the PSe-BO-based device.…”

Boosting the Fill Factor through Sequential Deposition and Homo Hydrocarbon Solvent toward Efficient and Stable All‐Polymer Solar Cells

“…Therefore, the highly ordered packing of polymers in blend film demonstrates a similar trend as the absorption result for the SD-Device. Meanwhile, the lamellar packing peaks that originated from the packing of alkyl chains were observed at ≈0.299 Å −1 (d lamellar = 21.0 Å) for the BC-processed film and at ≈0.296 Å −1 (d = 21.2 Å) for the SD-processed film in the in-plane (IP) direction, [38] which implies a dominant face-on orientation. Noticeably, the CCL for the SD-processed film (81.2 Å) is far higher than the BC-processed film (49.3 Å), proving that the lamellar packing in the pseudo-bilayer film is well-ordered compared with the BHJ film, which facilitates the charge transfer through the polymer backbone.…”

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

“…After device fabrication, high boiling point organic solvents used as an additive for OSCs will remain in the active layer. 23,24 Particularly, the remaining additive may accelerate photo-oxidative deterioration in the active layer, lowering PCE and reducing the lifetime of the organic photovoltaic (OPV) systems. 25 Compared to solvent additives, the solid additive is removed from the active layer after TA treatments.…”

“…25 Several treatments have been carried out to remove these additives using a high vacuum, including a slow drying procedure, washing out by antisolvents, and TA at high temperatures. 24 Despite this, these methods cannot resolve many of the abovementioned problems using additives to small-and large-area OPVs. Therefore, achieving a high PCE and good morphology with long-term stability is a vital but challenging requirement for additive-free OSCs for practical applications.…”