Over 15% efficiency all-small-molecule organic solar cells enabled by a C-shaped small molecule donor with tailorable asymmetric backbone

Chen

et al. 2021

Adv Funct Materials

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Promoted by uninterrupted materials and device innovation, organic solar cells have achieved impressive development. However, the complicated intermolecular interactions inside active layers are less understood. Herein, the intermolecular interactions are studied from the dual perspectives of acceptor/acceptor (A/A) and donor/acceptor (D/A), and how these interactions synergistically control the final efficiencies. Three small molecular acceptors (SMAs) are designed with different end-caps, which manipulate the crystallinity and electrostatic potential (ESP) distributions of acceptors, and accordingly, the A/A and D/A intermolecular interactions. The results show that SMA LA17 with low A/A interactions exhibits inferior performance around 12%, owing to its strong D/A interaction with donor PM6, which shapes too miscible morphology and increases charge recombination. Instead, LA16 with strong A/A interactions and moderate D/A interactions delivers improved bulk-heterojunction (BHJ) networks, and therefore, enhances charge transport and diminishes geminate or trap-assisted charge recombination. Consequently, PM6:LA16 records the competitive efficiency of up to 13.74% among the three systems. Therefore, this study deepens the synergistic or balancing effect of the D/A and A/A interactions on BHJ blends for efficient organic solar cells.

Section: (4 Of 11)mentioning

confidence: 63%

Balancing Intermolecular Interactions between Acceptors and Donor/Acceptor for Efficient Organic Photovoltaics

Han

Chen

et al. 2021

Adv Funct Materials

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“…Sometimes FRET is reported to boost the overall exciton diffusion efficiency through utilizing the additional excitons which did not change into charge transport (CT) and charge separated (CS) states. [ 6 ] In a word, FRET promotes photon harvesting, which simultaneously results in the improvement of exciton harvesting and exciton diffusion at the interfaces, hence leading to an improvement of charge generation.…”

Section: The Role Of Fretmentioning

confidence: 99%

“…Solution‐processable bulk‐heterojunction (BHJ) organic solar cells (OSCs) emerge as one of the strong promising candidates for alleviating the energy crisis and solving environmental issues, benefiting from their unique features of low cost, light weight, flexibility, semitransparency, and fast roll‐to‐roll method. [ 1–4 ] To date, many strategies have been developed to improve the power conversion efficiency (PCE) of the OSCs devices, which can be summarized as follows [ 5–8 ] : 1) It should be the offset between the highest occupied molecular orbital (HOMO) of the electron donor and lowest unoccupied molecular orbital (LUMO) of the electron acceptor, determining the open circuit voltage ( V OC ). 2) It will be beneficial to boost the short circuit current density ( J SC ) and fill factor (FF) to turn the work function of the transport layers for charge collection.…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Ternary Organic Solar Cells Based on Förster Resonance Energy Transfer

Yang

et al. 2021

Solar RRL

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Recently, Förster resonance energy transfer (FRET)‐based strategy has been successfully applied to promote the efficiencies of ternary blend organic solar cells (TOSCs). However, the intrinsic mechanism of FRET in the observed enhancement of efficiency has not been deconvolved unambiguously due to the complex photophysics mechanism. In this review, by deeply analyzing recent examples of FRET‐incorporated TOSCs, diverse framework structures of FRET pairs are summarized, then the theory, prerequisites, and the confirmation methods for FRET are discussed. In particular, the role of FRET theory in the photoconversion process is discussed in detail, including exciton harvesting, exciton diffusion, and charge generation. Finally, the existing challenges and future research directions of FRET applications in TOSCs are proposed.

“…Bulk heterojunction (BHJ) organic solar cells (OSCs) have undergone an impressive progress within the last few years due to the significant innovations in non-fullerene acceptors and device craft. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Over 18 % power conversion efficiency (PCE) and long-term device stability have been recorded in multiple cases. [5][6][7] Apart from the development of acceptors, interface engineering upon electrodes, that is, developing hole/electron transporting materials (HTMs/ETMs), is also a most effective strategy to further enhance the performance of OSCs to a new level.…”

Section: Introductionmentioning

confidence: 99%

Eliminating the Detrimental Effect of Secondary Doping on PEDOT : PSS Hole Transporting Material Performance

et al. 2021

ChemSusChem

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Secondary doping has a long history of use in conductivity enhancement in poly (3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS). However, very little research has addressed its detrimental effect on application performance of PEDOT : PSS in organic solar cells. Herein, it was shown that the uneven drying of secondary dopant-water mixture results in a nonuniform/continuous film structure, causing severe damage to the device efficiencies (dropping about 8 and 23 % for poly [(2,6-(4,8-bis(5-(2-ethylhexyl) and poly[(2,6-(4,8-bis(5-(2) cells, respectively) and thermal stabilities. Moreover, a simple yet robust dialysis treatment was proposed to solve the issue of noncontinuity and retain the secondary doping's advantages of quinoid structure simultaneously, thus demonstrating a significant enhancement in device performance. This study will be of great importance to the future exploration of the next generation of post-treatment strategy.