The photovoltaic performance of organic solar cells (OSCs) based on poly(3-hexylthiophene) (P3HT) has been steadily improved by developing novel non-fullerene acceptors (NFAs) in recent years. ...Herein, to further improve the performance of P3HT-based OSCs, a solid additive (SA4) and a typical solvent additive (DIO) were employed to process P3HT:ZY-4Cl-based OSCs, respectively. In comparison with the DIO-processed device, the SA4-processed one exhibits a more ordered molecular packing and more favorable phase separation, leading to the enhanced charge transport and reduced carrier recombination. As a result, the SA4-processed device delivers a power conversion efficiency (PCE) of 10.24%, which is much higher than that of DIO-processed counterpart (6.26%). This work reported an over 10% of PCE in P3HT-based OSCs for the first time, indicating the promising development of P3HT-based OSCs by morphological modulation.
Meniscus-guided coating exhibiting outstanding depositing accuracy, functional diversity, and operating convenience is widely used in printing process of photovoltaic electronics. However, current ...studies about hydrodynamic behaviors of bulk heterojunction ink are still superficial, and the key dynamic parameter dominating film formation is still not found. Here, we establish the principle of accurately evaluate the Hamaker constant and reveal the critical effect of precursor film length in determining flow evolution, the polymer aggregation, and final morphology. A shorter precursor film is beneficial to restraining chain relaxation, enhancing molecular orientation and mobility. On the basis of our precursor film-length prediction method proposed in this work, the optimal coating speed can be accurately traced. Last, a 18.39% power conversion efficiency has been achieved in 3-cm
cell based on bulk heterojunction fabricated by blade coating, which shows few reduce from 19.40% in a 0.04-cm
cell based on spin coating.
Semitransparent organic solar cells (ST‐OSCs) are considered as one of the most valuable applications of OSCs and a strong contender in the market. However, the optical band gap of current ...high‐performance ST‐OSCs is still not low enough to achieve the optimal balance between power conversion efficiency (PCE) and average visible transmittance (AVT). An N‐substituted asymmetric nonfullerene acceptor SN with over 40 nm bathochromically shifted absorption compared to Y6 was designed and synthesized, based on which the device with PM6 as donor obtained a PCE of 14.3 %, accompanied with a nonradiative voltage loss as low as 0.15 eV. Meanwhile, ternary devices with the addition of SN into PM6 : Y6 can achieve a PCE of 17.5 % with an unchanged open‐circuit voltage and improved short‐circuit current. Benefiting from extended NIR absorption and lowered voltage loss, ST‐OSCs based on PM6 : SN : Y6 were fabricated and the optimized device demonstrated a PCE of 14.0 % at an AVT of 20.2 %, which is the highest PCE at an AVT over 20 %.
An N‐substituted asymmetric nonfullerene acceptor SN with an over 40 nm bathochromically shifted absorption compared to Y6 is designed and synthesized. The PM6 : SN‐based binary cell exhibits the lowest nonradiative voltage loss of 0.15 eV ever achieved by organic solar cells (OSCs). Benefiting from extended NIR absorption and lowered voltage loss, PM6 : Y6 : SN‐based semitransparent (ST)‐OSCs, for the first time, achieve a power conversion efficiency of 14 % with an average visible transmittance over 20 %.
An integrated device architecture was constructed via vertical combination of planar and bulk heterojunctions by solution processing, where a cross-linked D-A copolymer (PBDTTT-Br25) was inserted ...between a PEDOT:PSS layer and the blended photoactive layer. PBDTTT-Br25 can readily undergo photo crosslinking to form an insoluble robust film via ultraviolet irradiation after solution–deposition, which enables the subsequent solution processing of a photoactive layer on the robust surface. The insertion of a pure PBDTTT-Br25 layer to build an integrated heterojunction could provide an additional donor/acceptor interface, which enables hole transport to the anode without interruption, thereby reducing the charge carrier recombination probability. The power conversion efficiency (PCE) of the polymer solar cell (PSC) with the integrated architecture reaches 5.24% under an AM1.5G illumination of 100 mW/cm2, which is increased by 65%, in comparison with that of the reference single heterojunction device (3.17%), under the same experimental conditions.
Two wide band gap (WBG) polymers based on thiophene-thiazolothiazole (TTz) units, PBT-TTz and PBT-S-TTz, were synthesized. Both polymers showed absorption onsets at 635 nm in solid films. Although ...PBT-TTz and PBT-S-TTz are WBG materials with relatively narrow absorption spectra, they have great potential for constructing high-performance polymer solar cells (PSCs). By replacing the alkyl side chain of PBT-TTz with an alkylthiol side chain, the HOMO level of PBT-S-TTz was lowered to −5.45 eV. A PCE of 7.92% was then obtained in a single-junction PSC device based on a PBT-S-TTz:PC
71
BM active layer. Moreover, high-performance fullerene-free PSCs were fabricated using these polymers and a high PCE of 8.22% was achieved. This work demonstrates that TTz-based polymers PBT-TTz and PBT-S-TTz are promising candidates as efficient WBG polymers for constructing high-performance PSC devices.
Efficient fullerene-based and fullerene-free PSCs were fabricated based on two wide band gap polymers PBT-TTz and PBT-S-TTz.
In article number 1803703, Jianhui Hou, Maria Antonietta Loi, and co‐workers introduce an ionic conjugated polymer, PCP‐Na, as the hole‐extraction layer in a half‐tin and half‐lead perovskite solar ...cell. They find that PCP‐Na helps to reduce the charge recombination, giving rise to Sn:Pb‐based perovskite solar cells with superior performance compared to those using poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as the hole‐extracting layer.
A new conjugated polymer utilizing diketopyrrolopyrrole (DPP) and benzo1,2-
c
:4,5-
c
′dithiophene-4,8-dione (BDD) units as the backbone framework was designed, synthesized, and applied in polymer ...solar cells. A high efficiency of 9.18% was obtained using phenyl-C
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-butyric acid methyl ester (PC
71
BM) as acceptor, which was among the best results obtained for DPP-based photovoltaic polymers. Absorption spectra indicated that the new polymer exhibits a narrow optical band-gap and strong aggregation behavior in the solution state. It was found that by dissolving the donor and acceptor in different solvents and then mixing them before film casting, better performing solar cell devices and distinct film morphology could be achieved, rather than by dissolution in one solvent. Small-angle neutron scattering (SANS) profiles showed that PC
71
BM in solution impaired polymer aggregate formation, because of its favorable interaction with the polymer chain. This study demonstrated the importance of manipulating the aggregation state in bulk heterojunction solar cell fabrication and revealed the influence of polymer-fullerene interplay on the blend film morphology.
A new conjugated polymer utilizing diketopyrrolopyrrole (DPP) and benzo1,2-
c
:4,5-
c
′dithiophene-4,8-dione (BDD) units as the backbone framework was designed, synthesized, and applied in polymer solar cells.
Although the power conversion efficiencies (PCEs) of polymer solar cells (PSCs) based on non-fullerene acceptors have been increasing rapidly over the last couple of years, little is known about the ...correlations between molecular structures and blend morphologies. In this work, we design and synthesize three acceptor-donor-core-donor-acceptor (A-D-C-D-A) type non-fullerene acceptors, HF-PCIC, HFO-PCIC and OF-PCIC, which possess the same electron-donating parts (D) and electron-accepting terminals (A), but different benzene-based cores (C). We observe that such minor chemical variations can lead to distinct differences in their photovoltaic properties. The resulting PSCs based on HF-PCIC with a 2,5-difluorobenzene core yield a good PCE of 10.97%, which is higher than those of HFO-PCIC and OF-PCIC based PSCs (8.36% and 9.09%). If the processing solvent is changed from chlorobenzene to chloroform, a further improved PCE of 11.49% is obtained for HF-PCIC-based PSCs due to the formation of finer phase separation domains. This is the highest value among the PSCs with non-fullerene acceptors possessing unfused cores. Through a series of characterization techniques, we disclose that the diverse benzene-based cores influence the molecular geometries of the three non-fullerene acceptors, resulting in varied molecular packing modes and film morphologies. The results suggest that the tuning of non-fullerene acceptors' geometries is an effective method to optimize the film morphology and thus the photovoltaic properties. The unfused-core in A-D-C-D-A small molecules provides a good building block to construct high-performance non-fullerene acceptors.
The molecular packing of three new non-fullerene acceptors with various benzene-based cores is systematically studied with the best power conversion efficiency of 11.49%.
In the field of organic photovoltaics (OPVs), significant progress has been made in tailoring molecular structures to enhance the open‐circuit voltage and the short‐circuit current density. However, ...there remains a crucial gap in the development of coordinated material design strategies focused on improving the fill factor (FF). Here, we introduce a molecular design strategy that incorporates electrostatic potential fluctuation to design organic photovoltaic materials. By reducing the fluctuation amplitude of IT‐4F, we synthesized a new acceptor named ITOC6‐4F. When using PBQx‐TF as a donor, the ITOC6‐4F‐based cell shows a markedly low recombination rate constant of 0.66×10−14 cm3 s−1 and demonstrates an outstanding FF of 0.816, both of which are new records for binary OPV cells. Also, we find that a small fluctuation amplitude could decrease the energetic disorder of OPV cells, reducing energy loss. Finally, the ITOC6‐4F‐based cell creates the highest efficiency of 16.0 % among medium‐gap OPV cells. Our work holds a vital implication for guiding the design of high‐performance OPV materials.
We designed and synthesized an outstanding acceptor material, namely ITOC6‐4F, characterized by a considerably low amplitude of electrostatic potential fluctuation (0.8 kcal/mol). The ITOC6‐4F‐based cell exhibits an extremely low bimolecular recombination rate constant of 0.66×10−14 cm3 s−1. Consequently, this has led to the attainment of a new record fill factor of 0.816 in binary organic photovoltaic cells.
Along with the advances in polymer solar cells (PSCs), the accurate evaluation of novel photovoltaic polymers with various band gaps is an important issue that should be concerned, as well as needs ...to be addressed at various research laboratories in the world. In this work, we have focused on PSCs by employing some of the most efficient and well-known low band gap (LBG) polymers, for instance, PBDTTT-C-T, PBDTBDD, PDPP3T, PTB7-Th, PSBTBT and PBDTTPD, and obtained the corresponding spectral-mismatch factors (MMFs) under various reference cell/solar simulator combinations. Generally, there still exists ±25% spectral error even for a simulator whose spectrum grade is labeled as AAA. The best way to accurately evaluate the power conversion efficiencies (PCEs) of LBG polymers is by choosing a combination of a spectral-matched-silicon-solar-cell (match to LBG polymer's spectral responsivity spectrum) and a Class AAA solar simulator. Furthermore, our results could provide guidance for the accurate measurements of organic molecules, perovskites, and related photovoltaic technologies.
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