Facile embedding of gold nanostructures in the hole transporting layer for efficient polymer solar cells

Recent Advances in 2D Metal Monochalcogenides

“…In such devices, 2D materials are widely used as in the active (donor) or in various interface/interconnecting layers for exciton generation or charge extraction. [196][197][198][199][200][201][202][203][204] A promising novel donor material should have direct bandgap (1.2-1.6 eV), high absorption coefficient, high carrier mobility, and low exciton binding energy, E B . A low E B is favorable for the efficient separation of photogenerated charge carriers.…”

Organic solar cells: Current perspectives on graphene‐based materials for electrodes, electron acceptors and interfacial layers

“…22,53,89 Being motivated by the increasing demand to overcome these limitations, graphene-based materials have recently emerged as promising HTL alternatives to PEDOT:PSS with advantages of solution-processability, flexibility, high optical transparency, tunable optical band gap, a high electron-blocking capability and competitive electrical conductivity. 204 In this regard, nanocomposites of GO with copper zinc tin selenide (Cu 2 ZnSnSe 4 ) nanocrystals treated with pyridine (CZTSe-Py), 128 gold nanostructures (Au NSs), 45 MoO 3 , 32 and copper(II) chloride (CuCl 2 ), 30 have been employed as HTLs in OSCs based on P3HT:PCBM, PTB7: PC 71 BM, poly[N-9 0 -heptadecanyl-2,7-carbazole-alt-5,5-(4 0 , 7 0 -di-2-thienyl-2 0 ,1 0 ,3 0 benzothiadiazole)] (PCDTBT): PC 71 BM), and PTB7-Th:PC 71 BM active layer blends. This resulted in devices with PCEs of 0.95%, 5.88%, 7.07% and 7.68%, respectively, which were comparable to the PEDOT:PSS control devices, and outperformed the devices based on pristine GO, as well as those without HTLs.…”

“…In this regard, nanocomposites of GO with copper zinc tin selenide (Cu 2 ZnSnSe 4 ) nanocrystals treated with pyridine (CZTSe‐Py), 128 gold nanostructures (Au NSs), 45 MoO 3 , 32 and copper(II) chloride (CuCl 2 ), 30 have been employed as HTLs in OSCs based on P3HT:PCBM, PTB7:PC 71 BM, poly[ N ‐9′‐heptadecanyl‐2,7‐carbazole‐alt‐5,5‐(4′,7′‐di‐2‐thienyl‐2′,1′,3′ benzothiadiazole)] (PCDTBT):PC 71 BM), and PTB7‐Th:PC 71 BM active layer blends. This resulted in devices with PCEs of 0.95%, 5.88%, 7.07% and 7.68%, respectively, which were comparable to the PEDOT:PSS control devices, and outperformed the devices based on pristine GO, as well as those without HTLs.…”

“…44 Among these drawbacks, short exciton diffusion lengths of 5 to 10 nm are normally overcome by trying to reduce the active layer thickness, which leads to poor absorption of light and low charge separation efficiency, and hence lowers the photo-generated current, and subsequently the PCE. 45,46 Furthermore, the low carrier mobility of the commonly used polymer materials (<10 −4 cm 2 V −1 s −1 ) often leads to the elimination of the separated electrons and holes by trapping or recombination taking place before reaching the electrodes, which greatly impairs device performance. 47 As a result, many researchers 22,[48][49][50][51][52] have been working towards adopting new materials, especially those with high carrier mobility, to provide more conductive networks in the photoactive layer.…”

“…Nevertheless, BHJ‐OSCs have demerits in terms of low optical absorbance in the photoactive layer, short exciton diffusion length, misalignment of the donor‐acceptor energy levels and low charge carrier mobility 44 . Among these drawbacks, short exciton diffusion lengths of ~5 to 10 nm are normally overcome by trying to reduce the active layer thickness, which leads to poor absorption of light and low charge separation efficiency, and hence lowers the photo‐generated current, and subsequently the PCE 45,46 . Furthermore, the low carrier mobility of the commonly used polymer materials (<10 −4 cm 2 V −1 s −1 ) often leads to the elimination of the separated electrons and holes by trapping or recombination taking place before reaching the electrodes, which greatly impairs device performance 47 .…”