Thermoelectric Properties of Solution‐Processed n‐Doped Ladder‐Type Conducting Polymers

Abstract

Ladder-type “torsion-free” conducting polymers (e.g., polybenzimidazobenzophenanthroline (BBL)) can outperform “structurally distorted” donor–acceptor polymers (e.g., P(NDI2OD-T2)), in terms of conductivity and thermoelectric power factor. The polaron delocalization length is larger in BBL than in P(NDI2OD-T2), resulting in a higher measured polaron mobility. Structure–function relationships are drawn, setting material-design guidelines for the next generation of conducting thermoelectric polymers

Complementary Logic Circuits Based on High‐Performance n‐Type Organic Electrochemical Transistors

“…The appearance of the new band at lower energy is ascribed to polaron-induced transitions. This is in agreement with the absorption spectra of molecularly n-doped BBL films, [15] and consistent with accumulation of charges in the electroactive BBL films.…”

“…[15] One of the prime requirements when using OECTs as a recording or sensor device in biological applications is stable operation in aqueous electrolyte media, without any degradation of the active material and/or drift of the device parameters. Figure 4A presents the stability of the current generated in a BBL spray-coated OECT (with thickness 90 nm) at V D = 0.5 V, upon successive gate voltage pulses (V G = 0.5 V, pulse length = 5 s) for 1 h. No current degradation is observed during this time, thus showing that BBL has a very good operational stability in water electrolytes, as also suggested by its high EA, [15] and in good agreement with previous studies. [21,23] In addition, reversible electrochemical switching between the reduced and neutral states is observed in cyclic voltammetry measurements performed in aqueous solution, under ambient conditions and without removing oxygen, even after 500 cycles ( Figure S6, Supporting Information).…”

High Seebeck Coefficient and Power Factor in n‐Type Organic Thermoelectrics

“…We note that the n-type data from ref. [16] are an exception to this rule and coincide with typical p-type data, see Figure S1 (Supporting Information). As a deviating dopant (TDAE) is used in this work and one of the polymers used, N2200 or P(NDI2OD-T2), also appears in the data following the ν 0 = 5 × 10 12 s −1 model curve, we attribute this exception to (morphological) problems associated with the particular dopant TDAE.…”

“…[2,3] In view of the limited number of reported data, it is still unclear whether n-type OTE also follow this power law, and different power law slopes have been reported. [15,16] Here, we introduce a novel, inverse-sequential doping procedure that mitigates the need for solvent orthogonality in conventional sequential doping to investigate the potential of The n-type thermoelectric properties of [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) are investigated for different solution-based doping methods. A novel inverse-sequential doping method where the semiconductor (PCBM) is deposited on a previously cast dopant 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-N,N-diphenylaniline film to achieve a very high power factor PF ≈ 35 µW m −1 K −2 with a conductivity σ ≈ 40 S m −1 is introduced.…”

“…[2,3] In view of the limited number of reported data, it is still unclear whether n-type OTE also follow this power law, and different power law slopes have been reported. [15,16] Here, we introduce a novel, inverse-sequential doping procedure that mitigates the need for solvent orthogonality in conventional sequential doping to investigate the potential of deposited on a previously cast dopant 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)-N,N-diphenylaniline film to achieve a very high power factor PF ≈ 35 µW m −1 K −2 with a conductivity σ ≈ 40 S m −1 is introduced. It is also shown that n-type organic semiconductors obey the −1/4 power law relation between Seebeck coefficient S and σ that are previously found for p-type materials.…”