Random copolymerization of polythiophene for simultaneous enhancement of in‐plane and out‐of‐plane charge transport for organic transistors and perovskite solar cells

Abstract

High-performance conjugated polymers for electronic applications can be developed by modulating an appropriate chemical structure that optimizes their crystal characteristics and charge-transport behavior. Herein, we demonstrated the simultaneous enhancement of the in-plane and out-of-plane charge transport of polythiophenes by random polymerization. We synthesized a polythiophene polymer by varying the ratio of two different dialkylsubstituted bi-thiophene and triethylene glycol-substituted mono-thiophene units; this polymer exhibited weakened orientation preferences of polymer crystallite films, a denser packing, and a more homogeneous surface morphology in comparison with its homopolymer analogue. Furthermore, this optimized random polymer afforded an enhanced in-plane mobility of 7.72 cm 2 V −1 second −1 , measured by field-effect transistor, and out-of-plane mobility of 8.86 × 10 −4 cm 2 V −1 second −1 , measured by space-charge-limitedcurrent device. These are respectively 2.4 times and 10 times higher than the mobilities of the homopolymer (field-effect mobility = 3.25 cm 2 V −1 second −1 and space-charge-limited-current mobility = 8.73 × 10 −5 cm 2 V −1 second −1). The enhanced charge transport in out-of-plane direction was also confirmed by fabricating perovskite solar cells using optimized polythiophene as a holetransporting material, which exhibited a higher efficiency of nearly 16.2% than the device with homopolymer analogue (12.0%).

EQCM Analysis of the Process of Electrochemical Insertion in Regioregular Alkyl-Susbtituted Polyterthiophene during n-Doping

“…Polythiophenes (PTs) constitute an interesting class of materials for the variety of advanced applications in which PTs play a pivotal role as active species. [1][2][3][4][5][6] The range of PTs applications spans from photovoltaics 7 (including perovskite solar cells 8,9 ), nonlinear optics 10 and sensors 11 to medicine, 12 cellular labelling, 13 organic electronics, 14 electroluminescence 15 and photonics 16 among others. 17,18 Such diversity and vastness of PTs applications are a consequence of fortunate combination of the intriguing electrical, electrochemical, optical and physical properties of PTs with the versatility and the easiness of the synthetic procedures through which chemically and physically stable PTs can be attained, 19 also in high yields, under mild operative conditions.…”

Electrodeposition as a Versatile Preparative Tool for Perovskite Photovoltaics: Aspects of Metallization and Selective Contacts/Active Layer Formation

“…Besides PAN, the electropolymerization of PEDOT on top of perovskite has been considered to show some limits in the performance of the resulting device. [47] A possible step further in the use of conductive polymers as selective contacts in perovskite PV could be moved by employing different types of poly-and oligo-thiophenes (especially the alkylsubstituted ones) [48][49][50][51][52][53][54][55] when this class of materials is deposited onto the substrate of interest via ED. [56,57] Besides the synthesis via electropolymerization, the class of polythiophenes (PTs) presents the additional advantage of being indifferently p- [58][59][60][61] and n-doped [62,63] via an electrochemical procedure of oxidation and reduction, respectively.…”

Concentrated perovskite photovoltaics enable minimization of energy loss below 0.5 eV under artificial light‐emitting diode illumination

“…Photovoltaic technology for generating electricity by collecting light energy has been intensively investigated due to the high demand for energy harvesting and photodetector applications 1‐4 . Particularly, concentrated photovoltaics (CPVs) have been developed as a cost‐effective light energy conversion technology; CPVs work by combining a photovoltaic (PV) system with a limited device area and an optical element that concentrates large amounts of light on a photo‐absorber 5 .…”

“…Photovoltaic technology for generating electricity by collecting light energy has been intensively investigated due to the high demand for energy harvesting and photodetector applications. [1][2][3][4] Particularly, concentrated photovoltaics (CPVs) have been developed as a cost-effective light energy conversion technology; CPVs work by combining a photovoltaic (PV) system with a limited device area and an optical element that concentrates large amounts of light on a photo-absorber. 5 From the viewpoint of energy conversion efficiency, CPVs also have a distinctive capability: compared to a counterpart device under nonconcentrated light, PV under concentrated light forms a wider splitting of the quasi-Fermi levels within the semiconducting absorbers, 6 attributed to an increased density of photo-generated carriers, and an enhanced open-circuit voltage (V OC ) of the PV system closer to the bandgap limit can therefore be produced.…”