Single‐Walled Carbon Nanotubes in Emerging Solar Cells: Synthesis and Electrode Applications

Abstract

years, because of growing concerns over the energy security. Among different types of photovoltaics, silicon solar cells give power conversion efficiencies (PCEs) of over 26% with excellent durability. This technology has already reached the market, and the products are readily available. However as recent technologies, such as flexible smartphones and IoT (internet of things), evolve into more versatile and portable electronics, there is a shift of demand from performance-centric technologies to versatility-oriented technologies. In other words, the paradigm is shifting to flexible, wearable, and light-weight electronic devices. Energy-generating devices are also following the same path. This means that the thin-film solar cell technologies, such as organic solar cells (OSCs) [1][2][3] and perovskite solar cells (PSCs), [4,5] are considered to be the wave of the future with their critical attributes of being ultrathin (<1 mm), light-weight, and solution-processable. [6] These emerging thin-film solar cells have the potential to equal or surpass the PCE of silicon solar cells while having major advantages in terms of production cost, enhanced design and a variety of new functionalities. Furthermore, tandem photovoltaics, [7] which are combined solar cells of PSCs, silicon solar cells, [8] or OSCs, [9,10] are another new and promising category for the future photovoltaic technology. Despite different names of solar cell types, the device structure is largely the same. They commonly share the typical configuration of one photoactive layer in the center, two charge selective layers above and below the active layer, and two electrodes at each end-at least one of which has to be transparent so that sunlight can pass through it. While there has been an intense efficiency race within the emerging thin-film solar cell community, less attention has been paid to other features, such as flexibility and stability. These traits can be enhanced by using new electrodes and charge-selective layers. Not only the functionalities but also photovoltaic performance is heavily dependent on the electrode and the charge-selective layers. Many scientists around the world, thus far, have focused on these layers by developing novel materials and modifying conventional materials to push the boundaries of current thin-film photovoltaic technology.Abundant and mechanically resilient carbon allotropes are composed of carbon atoms only, yet manifest different electronic properties depending on their configurations and arrangements. Of the carbon species, carbon nanotubes (CNTs) are promising materials to be incorporated into the thin-film solar cells owing to a wide range of properties ranging from conductors to semiconductors with different bandgaps based Emerging solar cells, namely, organic solar cells and perovskite solar cells, are the thin-film photovoltaics that have light to electricity conversion efficiencies close to that of silicon solar cells while possessing advantages in having additional functionalities, facile-processability, an...

High-performance transparent conducting films of long single-walled carbon nanotubes synthesized from toluene alone

“…Transparent conducting films (TCFs) composed of single-walled carbon nanotubes (SWCNTs) have outstanding electrical and optical properties, and consequently have high potential for various applications, such as thin-film transistors [1], solar cells [2], organic light-emitting diodes (OLEDs) [3] and strain sensors [4]. They are candidate materials for replacing indium tin oxide (ITO) films [5].…”

Rational design of highly efficient flexible and transparent p-type composite electrode based on single-walled carbon nanotubes

“…SWCNTs have rapidly been incorporated into the development of new types of solar cells comprising SWCNT films, graphene or a polymer and silicon or more recently perovskites [25,26,28,29]. They have the advantages of a simple structure and fabrication, low-cost and promising performance.…”

Investigation of charge interaction between fullerene derivatives and single‐walled carbon nanotubes

“…In addition, SWNTs can possess different energy bands depending on their diameters and chirality, ranging from semiconducting to metallic. 1,2 Such properties make SWNTs suitable for various device applications, specifically light-emitting displays, solar cells, and fieldeffect transistors (FETs). [3][4][5] Their device applicability can be strengthened further by improving conductivity and controlling their energy levels by means of doping.…”

“…[6][7][8] There have been myriad methods reported for the p-or n-type chemical doping of SWNTs. The p-type doping involves using acids, for example, H 2 SO 4 , [9][10][11][12][13][14] H 2 SO 3 , 13 HNO 3 , 7,10,14-22 HCl, 10 SOCl 2 , 11,21-27 CF 3 SO 3 H, 28 and Nafion, 29,30 as well as some oxidizing agents (= electron acceptors), such as tetrafluorotetracyano-p-quinodimethane, 31-33 I 2 , 11,34 IBr, 34 PBr 3 , 35 HSO 3 Cl, 34 KAuBr 4 , 34 AuCl 3 , [36][37][38][39] MoO x , 40 NO 2 ,41,42 CuCl 2 / Cu(OH) 2 , 43 and [(CF 3 SO 2 ) 2 N] − . [44][45][46][47] The n-type dopants are generally reducing agents (= electron donors), namely, alkali metals (K- [48][49][50][51][52] or Na-based dopants 52 ), N 2 H 4 , 22,53,54 aniline, 11 polyaniline, 53 ethylene diamine, 11 NH 3 ,42 polymer PEI,…”