Aggregation‐Induced Multilength Scaled Morphology Enabling 11.76% Efficiency in All‐Polymer Solar Cells Using Printing Fabrication

Abstract

resulting in inefficient charge separation and collection. [7][8][9] However, recent progresses show quite steep climbing of power conversion efficiency (PCE) for all-PSCs, reaching a value over 10%, [10][11][12] under systematic optimization, leaving a large gap to be filled in understanding the mechanism of morphology evolution. Polymer blends that reach nanoscaled phase separation in organic photovoltaic (OPV) application have distinctive advantages. They are more suitable for printing fabrication because of their good filmforming ability and mechanical flexibility, prominent device stability, and readily tunable ink viscosity. [13][14][15][16][17] Such benefits make all-PSC unique in scalable OPV fabrication, which also leads to boosted interest in understanding and manipulating the morphology. Initiative efforts on all-PSC printing have been surveyed, showing PCEs way below device made by spin-coating. [16,18] The mystery lies in morphology control, of which BHJ thin film is typical nonequilibrium nature that film-drying kinetics dictates the final nanostructure composed of crystalline networks and mixed and phase-separated domains. [19][20][21] It has been shown that solar cells using polymer:non-fullerene acceptor blends processed by slot die printing have exceed 11% in PCE, [22][23][24][25][26][27][28] from which we think that fine-tuning of morphology in all-PSCs could reach a similar level once a All-polymer solar cells (all-PSCs) exhibit excellent stability and readily tunable ink viscosity, and are therefore especially suitable for printing preparation of large-scale devices. At present, the efficiency of state-of-the-art all-PSCs fabricated by the spin-coating method has exceeded 11%, laying the foundation for the preparation and practical utilization of printed devices.A high power conversion efficiency (PCE) of 11.76% is achieved based on PTzBI-Si:N2200 all-PSCs processing with 2-methyltetrahydrofuran (MTHF, an environmentally friendly solvent) and preparation of active layers by slot die printing, which is the top efficient for all-PSCs. Conversely, the PCE of devices processed by high-boiling point chlorobenzene is less than 2%. Through the study of film formation kinetics, volatile solvents can freeze the morphology in a short time, and a more rigid conformation with strong intermolecular interaction combined with the solubility limit of PTzBI-Si and N2200 in MTHF results in the formation of a fibril network in the bulk heterojunction. The multilength scaled morphology ensures fast transfer of carriers and facilitates exciton separation, which boosts carrier mobility and current density, thus improving the device performance. These results are of great significance for large-scale printing fabrication of high-efficiency all-PSCs in the future. Polymer Solar Cells

Impact of Noncovalent Sulfur–Fluorine Interaction Position on Properties, Structures, and Photovoltaic Performance in Naphthobisthiadiazole‐Based Semiconducting Polymers

“…Recent studies of nonfullerene n‐type materials have further enhanced the performance of OPVs . In addition, semiconducting polymers as the n‐type material have also been intensively studied …”

Understanding the Interplay of Transport‐Morphology‐Performance in PBDB‐T‐Based Polymer Solar Cells

“…Zhan and co‐workers first reported efficient nonfullerene solar cells using a newly designed conjugated molecular acceptor ITIC, which outperforms conventional PCBM‐based devices. Meanwhile, the PCE of polymer–polymer (all‐polymer) solar cells have also rapidly progressed and now exceed 11% . Currently, PSC research is mainly focused on two aspects: 1) exploring more solar‐efficient materials with a focus on nonfullerene acceptors and 2) device engineering to improve charge transport and recombination.…”

In situ Measuring Film-Depth-Dependent Light Absorption Spectra for Organic Photovoltaics

“…As one of the effective approaches to utilize solar energy converting energy, photovoltaics have received extensive attention. Achieving high-efficiency, large-area manufacture, and excellent environmental stability are the goals (Liu et al, 2015;Niu et al, 2018;Fan et al, 2019;Xu et al, 2019a,b;Zhu et al, 2019;Zhang et al, 2020). Especially, organic photovoltaic devices (OPVs) using solution-processible donor-acceptor bulk heterojunction (BHJ) as photon-harvesting active layer are attractive for next-generation flexible photovoltaic modules (Li et al, , 2018Lin et al, 2012;Heeger, 2014;Dong et al, 2019).…”