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Abnormal exciton generation obtained from the theoretical model. The graphs present the exciton generation of the Ag-grating-inverted devices over that of the Ag-planar-inverted ones, which is defined as log10(Gg(r)/Gp(r)). The active layer thickness for both types of devices is set to be the same. The exciton generation of the Ag-planar device is nonzero at the region corresponding to the nanopatterned anode of the Ag-grating device where zero exciton generation is achieved. (a) s polarization for the square grating; (b) p polarization for the square grating; (c) unpolarization for the square grating; (d) s polarization for the sinusoidal grating; (e) p polarization for the sinusoidal grating; (f) unpolarization for the sinusoidal grating.
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As a fundamental electrostatic limit, space charge limit (SCL) for photocurrent is a universal phenomenon and of paramount importance for organic semiconductors with unbalanced photocarriers mobility and high exciton generation. Here we proposed a new plasmonic-electrical concept to manipulate electrical properties of organic devices including phot...
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Context 1
... understand above experimental findings particularly for the SCL elimination in the Ag-grating-inverted OSCs at room temperature, the physical process is theoretically modeled with a mechanistic insight. Through rigorously solving Maxwell's equations 51 , we calculate the ratio of exciton generation of the Ag-grating-inverted device to that of the Ag-planar-inverted one, which is plotted in Figure 4 41 and surface plasmon coupled waveguide mode 31 contribute to the exciton hot spots. Most importantly, the extraordinarily dense exciton generation can be found very near to the Ag-grating anode. ...
Context 2
... shown in Figure 1(b) and Figure 4, the abnormally redistrib- uted holes (resulting from the dense exciton generation) just trans- port a short path before collected by the anode. To investigate the influence of the short transport path of holes on electrical properties of OSCs, semiconductor equations (Poisson, drift-diffusion, and continuity equations) 52-55 are solved self-consistently (See Theoretical Model at Methods Section). ...
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Citations
... Thermal annealing is one of the mechanisms to improves polymers crystallization and promotes charge transfer between molecules. The discrepancy in mobility between electrons and holes can lead to an imbalance charge transport, which can increase for non-geminate charge recombination in polymer solar cells [53,54]. The use of plasmonic metal NPs, in a polymer photoactive layer, increases not only the optical absorption the polymer film but also has a great impact on the charge mobility in the medium. ...
Narrow width of optical absorption of conducting polymers and photons energy losses have been the challenges for fabricating highly efficient thin-film organic solar cell. Nickel-doped silver nanoclusters (Ni/Ag NCs) are employed here to capture more photons using polymers blend solar absorber medium to improve solar cell performances. The poly-3-hexylthiophene and (6-6)phenyl-C61-butyric acid methyl ester molecules blend were used a solar absorber layer in this investigation. The solar cells fabricated with NCs exhibited enhanced opt-electronic properties compared to the reference solar cell. Consequently, the experimental results suggest that the power conversion efficiency (PCE) has substantially increased with the incorporations of NCs in absorber layer, which is dependent on the concentrations of NCs in the medium. The maximum PCE achieved, in this work, is η\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\eta $$\end{document} = 6.2% at 2% of NCs by weight, which has exhibited to the lowest energy losses compared to other doping levels. This improvement in PCE is attributed to the occurrence of local surface plasmon resonance effect due to the inclusion of Ni/Ag NCs in polymer matrix. The results provide valuable insights on the use of Ni/Ag NCs for efficient photons capture in thin-film polymers blend medium.
... Then, we studied PR in the polymer films on different Ag surfaces as they are more relevant for organic optoelectronic applications (Ag is a metal suitable for use as an electrode in devices) [24,[56][57][58]. Due to the intrinsic chain conformation, it was found that RR-P3HT films were the roughest even on the glass substrate. ...
... The charge transport processes have been investigated using the measured space charge limited current (SCLC) taken under dark conditions. 38,42,43 The SCLC data provided in Figure 5d show the dominant charge transport processes as the result of NP incorporation in the solar cells. The SCLC is a charge transport property, where all defects are filled and current is saturated in the medium. ...
Ag/CuPO 4 nanocomposite was successfully synthesized using wet chemistry for potential application as a mechanism to suppress charge recombination and harvest more photons in thin-film organic solar cells (TFOSCs). The morphological and optical properties of the nanocomposite were studied using high-resolution electron microscopy and UV−vis spectroscopy. The Ag/CuPO 4 nano-composite exhibited a semispherical geometry which is suitable for the occurrence of localized surface plasmon resonance (LSPR) and light scattering in a dielectric medium. Conventional device architecture is employed that uses a solar absorber composed of a poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C 61-butyric acid methyl ester (PCBM) blend with and without the nanocomposite. As a result, significant changes in the device performances were observed by the incorporation of the metal nanocomposite, where the experimental evidence suggested that the doped active layer outperformed the undoped ones. Consequently, the best power conversion efficiency (PCE) grew by nearly 95% compared to the reference cell. Furthermore, the measured photocurrents are found to be dependent on the concentration of the nanocomposite in the absorber layer. In this article, the effects of metal nanocomposite are discussed in terms of the phenomena of local surface plasmon resonance and far-field scattering in the photoactive medium of TFOSCs.
... Yet, the impact of a patterned device electrode on the OSC electrical characteristic is not just limited to charge collection mechanisms at the active layer/electrode interface. Compared to solar cells with a planar back electrode surface geometry, the excitation of PSPs induces a strong spatial confinement of the optical fields in close vicinity to the patterned electrode interface, shifting the spatial photocurrent generation from the (transparent) front electrode to the back electrode [37][38][39]. The PSP-related modification of the spatial photocurrent generation profile when patterning the back electrode interface, therefore, alters the mean path length light-induced photocarriers need to cover until extraction at the respective device electrodes. ...
... Therefore, a variation of the photocarrier extraction path length could significantly affect the impact of non-geminate recombination on the harvested photocurrents yields. Recently, the PSPinduced variation of the photocarrier mean extraction path length in presence of a patterned back electrode interface was shown to mitigate non-geminate recombination caused by the introduction of space charges [38]. This mechanism, however, was only observed at inverted solar cells (i.e., patterned anode interface) but not at devices bearing a standard device architecture (i.e., patterned cathode interface) [38]. ...
... Recently, the PSPinduced variation of the photocarrier mean extraction path length in presence of a patterned back electrode interface was shown to mitigate non-geminate recombination caused by the introduction of space charges [38]. This mechanism, however, was only observed at inverted solar cells (i.e., patterned anode interface) but not at devices bearing a standard device architecture (i.e., patterned cathode interface) [38]. Although this report meticulously examines the space charge limited photocurrent extraction characteristic of standard and inverted P3HT:PCBM solar cells, it does not specifically address the impact of a patterned back electrode interface at different charge extraction regimes or when varying the applied pattern period of the utilized 2D pattern structure [38]. ...
Unlabelled:
Nano-patterning the semiconducting photoactive layer/back electrode interface of organic photovoltaic devices is a widely accepted approach to enhance the power conversion efficiency through the exploitation of numerous photonic and plasmonic effects. Yet, nano-patterning the semiconductor/metal interface leads to intertwined effects that impact the optical as well as the electrical characteristic of solar cells. In this work we aim to disentangle the optical and electrical effects of a nano-structured semiconductor/metal interface on the device performance. For this, we use an inverted bulk heterojunction P3HT:PCBM solar cell structure, where the nano-patterned photoactive layer/back electrode interface is realized by patterning the active layer with sinusoidal grating profiles bearing a periodicity of 300 nm or 400 nm through imprint lithography while varying the photoactive layer thickness (L PAL ) between 90 and 400 nm. The optical and electrical device characteristics of nano-patterned solar cells are compared to the characteristics of control devices, featuring a planar photoactive layer/back electrode interface. We find that patterned solar cells show for an enhanced photocurrent generation for a L PAL above 284 nm, which is not observed when using thinner active layer thicknesses. Simulating the optical characteristic of planar and patterned devices through a finite-difference time-domain approach proves for an increased light absorption in presence of a patterned electrode interface, originating from the excitation of propagating surface plasmon and dielectric waveguide modes. Evaluation of the external quantum efficiency characteristic and the voltage dependent charge extraction characteristics of fabricated planar and patterned solar cells reveals, however, that the increased photocurrents of patterned devices do not stem from an optical enhancement but from an improved charge carrier extraction efficiency in the space charge limited extraction regime. Presented findings clearly demonstrate that the improved charge extraction efficiency of patterned solar cells is linked to the periodic surface corrugation of the (back) electrode interface.
Supplementary information:
The online version contains supplementary material available at 10.1007/s00339-023-06492-6.
... The plasmonic asymmetric modes of Au NSs enhanced the optical absorption of the active layer and the balance of photogenerated charges by shortening transport path length in the HTL. The localized plasmonic effect of NPs manipulates transport paths of photogenerated carriers in bulk heterojunction OSCs and thus reduces the charge recombination sites and the space-charge-limit effect [147,148]. Li et al. reported comparable results by applying Ag nanoprisms to achieve higher PCE through the improvement in the broadband absorption [149]. Remya et al. performed a study between dehydrated and di-hydrated WO 3 films as HTL in the inverted P3HT:PC 61 BM and PTB7:PC 71 BM cells [150]. ...
Global energy demand is increasing; thus, emerging renewable energy sources, such as organic solar cells (OSCs), are fundamental to mitigate the negative effects of fuel consumption. Within OSC’s advancements, the development of efficient and stable interface materials is essential to achieve high performance, long-term stability, low costs, and broader applicability. Inorganic and nanocarbon-based materials show a suitable work function, tunable optical/electronic properties, stability to the presence of moisture, and facile solution processing, while organic conducting polymers and small molecules have some advantages such as fast and low-cost production, solution process, low energy payback time, light weight, and less adverse environmental impact, making them attractive as hole transporting layers (HTLs) for OSCs. This review looked at the recent progress in metal oxides, metal sulfides, nanocarbon materials, conducting polymers, and small organic molecules as HTLs in OSCs over the past five years. The endeavors in research and technology have optimized the preparation and deposition methods of HTLs. Strategies of doping, composite/hybrid formation, and modifications have also tuned the optical/electrical properties of these materials as HTLs to obtain efficient and stable OSCs. We highlighted the impact of structure, composition, and processing conditions of inorganic and organic materials as HTLs in conventional and inverted OSCs.
... The effects of adding plasmonic nanospheres (NSs) over the top electrode of the OSC have been investigated for different metals-gold, silver, and aluminum. Although the effect of metallic nanoparticles on the electrical properties such as PCE and fill factor (FF) have been reported, [42][43][44][45] this paper focuses primarily on the improvement in the optical properties such as absorption in the different active layers due to the presence of the metallic nanoparticles. The effect of varying the NS size and periodicity on the absorption as well as J SC of these tandem OSCs was also investigated. ...
A triple‐junction tandem organic solar cell (OSC) having polymer active materials, P3HT:PC70BM, Si‐PCPDTBT:PC70BM, and PMDPP3T:PC70BM is presented. These active layer materials cover a 300 nm to 1000 nm broad solar spectrum and have minimally overlapping narrow absorption bands. The performance of the triple‐junction tandem OSC was improved by introducing plasmonic nanospheres (NSs) over the top electrode of the OSC. The OSCs were modeled in finite‐difference time‐domain (FDTD) to optimize the performance of the NSs. Nanospheres of three plasmonic materials—gold (Au), silver (Ag), and aluminum (Al) were individually simulated over the top electrode of the OSCs. The NSs affect absorption in the active layer materials, around their respective plasmonic resonance peaks. The low‐cost Al NSs enhance light trapping in the top and middle subcells, leading to a 14% improvement in overall short circuit current density (JSC) of the triple‐junction tandem OSC in comparison with that of the reference OSC without any NSs. It is also observed that while the enhancement of the overall JSC of the triple‐junction tandem OSC due to the Al NSs is greater than that due to the Ag NSs, the presence of Au NSs leads to a decrease in the overall JSC in comparison with that of the reference OSC.
... The S-shape predominantly appears in the illuminated J-V curve which implies that it is related to the photocurrent in the device as well. Therefore, we have estimated the photocurrent (J ph ) by subtracting the dark current from the light current (J ph = J L −J D ) and plotted against the effective applied bias V eff (V 0 −V) on a logarithmic scale for both device A (with an S-shape) and device B (without an S-shape), where V 0 is the compensation voltage at which dark and light current are equal (J L = J D ), and it is almost equal to the built-in potential of OSCs, 17,18 whereas device B does not show any S-shaped curve. Here, the effective applied bias shows the strength of the electric field inside the device. ...
Zinc oxide (ZnO) has great potential as an electron transport layer (ETL) for producing efficient and stable organic solar cells. The effect of ozone treatment on ZnO working as the ETL in the organic solar cell has been studied by analyzing crystallinity, the defect density of states, and charge carrier dynamics from transient absorption spectroscopy to understand its role in the improvement in the interface between ETL and active layers. We have observed that a 10-minute continuous ozone treatment of ZnO film demonstrates improvement in its crystallinity leading to a 23% increment in short circuit current. The improvement in the crystallinity has been confirmed by the morphological and structural analysis using SEM and GIXRD. These analyses reveal the formation of a flake-like structure and an increase in peak intensity in GIXRD. It has been observed that ozone exposure has significantly affected the carrier recombination resistance, ideality factor of the device. From transient absorption spectroscopy, it has been found that for 10 min ozone-treated ZnO film has an average carrier transport time (661.79 ps), which is smallest as compared to untreated film or over treated film leading to faster carrier extraction through ETL. Further, the study of defect density of states shows that optimized ozone-treated film show 22.08% decrease in defects as compared to the control device, which primarily reflected as the improvement in the current density leading to increase in device efficiency from 2.95% to 3.75%.
... Because of this, there is a great interest in thin-film solar cells having film thicknesses in the range of 1-2 m [3,4]. Organic solar cells (OSCs) have received intensive study due to their promising advantages such as low cost, transparency, ease of processing and mechanical flexibility [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. ...
... Increasing the thickness would result in higher carrier's recombination rate due to the carrier's low mobility and short excitation length of the OSC' polymer. Many techniques to overcome the trade-off between carrier separation and light absorption have been reported [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][92][93][94][95][96][97]. Incorporating metallic nano-particles (NP) in OSCs enhances the light trapping [92]. ...
... When the diameter of the NPs are close to 50 nm, the scattering of photons is comparable in both forward and backward directions. Increasing the diameter of NPs above 50 nm leads to an increase in the scattering in the backward direction, while decreasing below 50 nm leads to an increase in the scattering in the forward direction [5,6,92]. ...
With the advances in the field of plasmonics, techniques for trapping and localizing light have become more feasible at the nanoscale. Several works have shown that plasmonics-based photovoltaic devices have yielded an improved absorption capability, enabling the design of thin-layered photovoltaic absorbers. In this review, we shed light on recent advances that employ plasmonics and nano-sized structures and thin-film technologies intended to increase solar cell efficiency. In this work, we provide an overview of the challenges associated with developing high-efficiency solar cells. Despite significant efforts by numerous groups to improve the efficiency of solar cells, practical realization of these concepts has yet to materialize. The conclusions made here hope to encourage researchers to re-examine the factors and challenges that could have created barriers to full realization of all concepts proposed over the past 15 years. In fact, because of the immense impact of improving the efficiency of solar cells on the environment and economy, it is hoped that this review encourages new technology paradigms that can be translated into commercially viable products.
... Because of this, there is a great interest in thin-film solar cells having film thicknesses in the range of 1-2 m [3,4]. Organic solar cells (OSCs) have received intensive study due to their promising advantages such as low cost, transparency, ease of processing and mechanical flexibility [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. ...
... Increasing the thickness would result in higher carrier's recombination rate due to the carrier's low mobility and short excitation length of the OSC' polymer. Many techniques to overcome the trade-off between carrier separation and light absorption have been reported [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][92][93][94][95][96][97]. Incorporating metallic nano-particles (NP) in OSCs enhances the light trapping [92]. ...
... When the diameter of the NPs are close to 50 nm, the scattering of photons is comparable in both forward and backward directions. Increasing the diameter of NPs above 50 nm leads to an increase in the scattering in the backward direction, while decreasing below 50 nm leads to an increase in the scattering in the forward direction [5,6,92]. ...
With the advances in the field of plasmonics, techniques for trapping and localizing light have become more feasible at the nanoscale. Several works have shown that plasmonics-based photovoltaic devices have yielded an improved absorption capability, enabling the design of thin-layered photovoltaic absorbers. In this review, we shed light on recent advances that employ plasmonics and nano-size structures and thin-film technologies intended to increase solar cell efficiency. In this work, we provide an overview of the challenges associated with developing high-efficiency solar cells. Despite significant efforts by numerous groups to improve the efficiency of solar cells, practical realization of these concepts have yet to materialize. The conclusions made here hope to encourage researchers to reexamine the factors and challenges that could have created barriers to full realization of all concepts proposed over the past 15 years. In fact, because of the immense impact of improving the efficiency of solar cells on the environment and economy, it is hoped that this review encourages new technology paradigms that can be translated into commercially viable products.
... 41−43 Additionally, it has been reported that inverted organic solar cells (OSCs) incorporating plasmonic metasurfaces are exempt from the space charge accumulation limit, which prevents deterioration of the electrical properties compared to planar inverted and conventional devices. 44,45 Therefore, with proper material and device considerations, plasmonic metasurfaces can be integrated into optoelectronic devices in ways that benefit device efficiency. ...
Metal electrodes are playing an increasingly important role in controlling photon absorption and in promoting optimal light management in thin-film semiconductor devices. For organic optoelectronic devices, the conventional fabrication approach is to build the device on top of a transparent electrode, with metal electrode deposition as the last step. This makes it challenging to control the surface of the metal electrode to promote good light management properties. An inverted fabrication approach that builds the device on top of a metal electrode, makes it possible to control the morphology of the metal surface independently of the organic semiconductor active layer to achieve a variety of photonic and plasmonic behaviors useful for devices. Yet, there are few reports of inverted fabrication of organic optoelectronic devices and its impacts on device properties. Silver (Ag) is the most suitable metal for fabrication of nanostructured electrodes with plasmonic behavior (i.e., plasmonic electrodes) because of its low parasitic absorption loss and high reflectivity. In this project, we describe the facile fabrication of silver nanoparticle (AgNP) aperiodic plasmonic metasurfaces and study their physical and optical characteristics. Then, we investigate the photonic and electrical behavior of the aperiodic plasmonic metasurfaces when interfaced with poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) organic semiconducting polymer thin films. The luminescence quantum yield of F8BT thin films increases from 29% on planar Ag up to 66% on AgNP metasurfaces (AgNP MS) due to the Purcell Effect and the improved extraction of emission coupled to surface plasmon polariton (SPP) modes. In particular, we show that plasmonic enhancement can overcome ohmic losses associated with metals and metal-induced exciton quenching. According to the current-voltage characteristics of hole-only devices with and without aperiodic plasmonic metasurfaces, we conclude that AgNP aperiodic plasmonic metasurfaces have comparable electrical behavior to planar metal electrodes while having superior light management capability.
