| 1. |
- Guo, Han, et al.
(author)
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Transition metal-catalysed molecular n-doping of organic semiconductors
- 2021
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In: Nature. - London, United Kingdom : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 599:7883, s. 67-73
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Journal article (peer-reviewed)abstract
- Electron doping of organic semiconductors is typically inefficient, but here a precursor molecular dopant is used to deliver higher n-doping efficiency in a much shorter doping time. Chemical doping is a key process for investigating charge transport in organic semiconductors and improving certain (opto)electronic devices(1-9). N(electron)-doping is fundamentally more challenging than p(hole)-doping and typically achieves a very low doping efficiency (eta) of less than 10%(1,10). An efficient molecular n-dopant should simultaneously exhibit a high reducing power and air stability for broad applicability(1,5,6,9,11), which is very challenging. Here we show a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants. Incorporation of a transition metal (for example, Pt, Au, Pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes (for example, Pd-2(dba)(3)) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased eta in a much shorter doping time and high electrical conductivities (above 100 S cm(-1); ref. (12)). This methodology has technological implications for realizing improved semiconductor devices and offers a broad exploration space of ternary systems comprising catalysts, molecular dopants and semiconductors, thus opening new opportunities in n-doping research and applications(12, 13).
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| 2. |
- Sun, Huiliang, et al.
(author)
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A Narrow-Bandgap n-Type Polymer with an Acceptor-Acceptor Backbone Enabling Efficient All-Polymer Solar Cells
- 2020
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In: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 32
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Journal article (peer-reviewed)abstract
- Narrow-bandgap polymer semiconductors are essential for advancing the development of organic solar cells. Here, a new narrow-bandgap polymer acceptor L14, featuring an acceptor-acceptor (A-A) type backbone, is synthesized by copolymerizing a dibrominated fused-ring electron acceptor (FREA) with distannylated bithiophene imide. Combining the advantages of both the FREA and the A-A polymer, L14 not only shows a narrow bandgap and high absorption coefficient, but also low-lying frontier molecular orbital (FMO) levels. Such FMO levels yield improved electron transfer character, but unexpectedly, without sacrificing open-circuit voltage (V-oc), which is attributed to a small nonradiative recombination loss (E-loss,E-nr) of 0.22 eV. Benefiting from the improved photocurrent along with the high fill factor andV(oc), an excellent efficiency of 14.3% is achieved, which is among the highest values for all-polymer solar cells (all-PSCs). The results demonstrate the superiority of narrow-bandgap A-A type polymers for improving all-PSC performance and pave a way toward developing high-performance polymer acceptors for all-PSCs.
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| 3. |
- Tang, Yumin, et al.
(author)
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Two Compatible Polymer Donors Enabling Ternary Organic Solar Cells with a Small Nonradiative Energy Loss and Broad Composition Tolerance
- 2020
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In: Solar RRL. - : Wiley-VCH Verlagsgesellschaft. - 2367-198X. ; 4:11
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Journal article (peer-reviewed)abstract
- High-performance nonfullerene ternary organic solar cells (OSCs) with two polymer donors are less frequently reported because of the limited numbers of efficient polymer donors with good compatibility. Herein, a wide-bandgap polymer P1 with a deep-lying highest occupied molecular orbital (HOMO) level is incorporated as the third component into the benchmark PM6:Y6 binary system to fabricate ternary OSCs. The introduction of P1 not only leads to extended absorption coverage and forms a cascade-like energy level alignment but also shows excellent compatibility with PM6, resulting in a favorable morphology in the ternary blend. More importantly, P1 possesses a deeper HOMO level (-5.6 eV) than most well-known donor polymers, which enables resulting ternary OSCs with an improved open-circuit voltage. As a result, the optimized ternary OSCs with 40 wt% P1 in donors achieve a power conversion efficiency (PCE) of 16.2% with a small nonradiative recombination loss of 0.23 eV, which is among the highest values of ternary OSCs based on two polymer donors. In addition, the ternary OSCs show a broad composition tolerance with a high PCE of over 14% throughout the whole blend ratios. These results provide an effective approach to fabricate efficient ternary OSCs by synergizing two wide-bandgap polymer donors.
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