Layer In Solar Cells Research Articles

Columnar self-assembled heteroatom bay-annulated perylene bisimide as passivating layer for high performance perovskite solar cells

The interfaces within Perovskite solar cells (PSCs) are imperative for regulating defects, managing carrier dynamics, preventing ion migration, optimizing energy band alignment, and controlling morphology. The interfaces amidst the absorber layer and the hole transport layer (HTL) pose challenges related to ineffective charge extraction and charge recombination, necessitating enhancement. Spiro-OMeTAD is commonly utilized as p-type material in the HTL of planar architecture, entailing the inclusion of diverse additives to enhance solar cell efficiency, which can restrict device performance and stability. Herein, we explore the influence of a discotic liquid crystalline (DLCs) based semiconductor, a heteroatom bay-annulated perylene bisimide (PBI-SeO10), which is derived from tri-n-alkoxy anilines. Our study examines the function of PBI-SeO10 as an interfacial passivation layer within the perovskite/Spiro-OMeTAD interface, assessing its effects on both device performance and stability. Our results indicate that integrating PBI-SeO10 as a surface passivation layer not only aids in effective hole extraction from the perovskite layer but also substantially diminishes defects, leading to an improvement in overall device performance by approximately 7 %. Furthermore, PBI-SeO10 passivation also reduces ionic/molecular species diffusion into the device and provides good moisture resistivity leading to improved device stability.

Hierarchical Solid-Additive Strategy for Achieving Layer-by-Layer Organic Solar Cells with Over 19 % Efficiency.

Layer-by-layer (LbL) deposition of active layers in organic solar cells (OSCs) offers immense potential for optimizing performance through precise tailoring of each layer. However, achieving high-performance LbL OSCs with distinct solid additives in each layer remains challenging. In this study, we explore a novel approach that strategically incorporates different solid additives into specific layers of LbL devices. To this end, we introduce FeCl3 into the lower donor (D18) layer as a p-type dopant to enhance hole concentration and mobility. Concurrently, we incorporate the wide-band gap conjugated polymer poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) into the upper acceptor (L8-BO) layer to improve the morphology and prolong exciton lifetime. Unlike previous studies, our approach combines these two strategies to achieve higher and more balanced electron and hole mobility without affecting device open-circuit voltage, while also suppressing charge recombination. Consequently, the power conversion efficiency (PCE) of the D18+FeCl3/L8-BO device increases to 18.12 %, while the D18/L8-BO+PFO device attains a PCE of 18.79 %. These values represent substantial improvements over the control device's PCE of 17.59 %. Notably, when both FeCl3 and PFO are incorporated, the D18+FeCl3/L8-BO+PFO device achieves a remarkable PCE of 19.17 %. In summary, our research results demonstrate the effectiveness of the layered solid additive strategy in improving OSC performance.

Components and defect density optimization of FAxMA1-xPbI3 based on simulation for high performance perovskite solar cells

Choosing FA+/MA+ mixed-ion perovskite material as the active layer of the perovskite solar cells hold out the prospect of high efficiency and high stability. In this paper, the FA+/MA + ratio is modified to optimize the performance of FAxMA1-xPbI3-based perovskite solar cells utilizing SCAPS-1D. The results indicate that the PCE of the devices reached a minimum of 21 % when x is greater than or equal to 0.6 in FAxMA1-xPbI3(FTO/NiOx/FAxMA1-xPbI3/C60/BCP/Al). When x = 0.6, the impact of the bottom interface defects on the solar cell performance is dominant and the thickness of the active layer should be controlled within a range of 0.4 μm–0.8 μm, while the defect density of the layer is expected to be between 1013 1/cm3 and 1014 1/cm3. By optimizing the perovskite layer thickness, defect density and changing the type of back electrode material, the efficiency is reaching 25.74 % based on the device(FTO/NiOx/FA6MA4PbI3/C60/BCP/Au). This study provides theoretical guidance for experimental research on interface modification, defect passivation and manufacturing of high-efficiency FAxMA1-xPbI3-based perovskite solar cells.

Hierarchical Solid‐Additive Strategy for Achieving Layer‐by‐Layer Organic Solar Cells with Over 19 % Efficiency

AbstractLayer‐by‐layer (LbL) deposition of active layers in organic solar cells (OSCs) offers immense potential for optimizing performance through precise tailoring of each layer. However, achieving high‐performance LbL OSCs with distinct solid additives in each layer remains challenging. In this study, we explore a novel approach that strategically incorporates different solid additives into specific layers of LbL devices. To this end, we introduce FeCl3 into the lower donor (D18) layer as a p‐type dopant to enhance hole concentration and mobility. Concurrently, we incorporate the wide‐band gap conjugated polymer poly(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl) (PFO) into the upper acceptor (L8‐BO) layer to improve the morphology and prolong exciton lifetime. Unlike previous studies, our approach combines these two strategies to achieve higher and more balanced electron and hole mobility without affecting device open‐circuit voltage, while also suppressing charge recombination. Consequently, the power conversion efficiency (PCE) of the D18+FeCl3/L8‐BO device increases to 18.12 %, while the D18/L8‐BO+PFO device attains a PCE of 18.79 %. These values represent substantial improvements over the control device′s PCE of 17.59 %. Notably, when both FeCl3 and PFO are incorporated, the D18+FeCl3/L8‐BO+PFO device achieves a remarkable PCE of 19.17 %. In summary, our research results demonstrate the effectiveness of the layered solid additive strategy in improving OSC performance.

Small molecule perylene diimide derivatives with different bay site modifications as cathode interface layers for organic solar cells

Cathode interface layers (CILs) can effectively elevate the performance of organic solar cells (OSCs), and the development of CILs with high thickness insensitivity is the focus of commercializing OSCs. Perylene diimide (PDI) derivatives proved to be potential CILs, and bay modification could further adjust the coplanarity and optimize the film-forming properties of PDI-based CILs. Thus, two novel CILs with intermediate-sized spacer groups were synthesized (PDINN-P3P and PDINN-TPA). In contrast to PDINN-P3P with m-diphenylbenzene, PDINN-TPA with triphenylamine can form stronger self-doping between the side chain of triphenylamine and the PDI backbone, resulting in higher charge transport capacity and better interface regulation ability. PDINN-TPA-based OSCs demonstrated a higher power conversion efficiency (PCE) of 16.11 % in the PM6:Y6 system, outperforming the PCE of PDINN-P3P-based OSCs (15.00 %). Meanwhile, PDINN-TPA expressed a favorable thickness processing range, a PCE of 14.19 % can be maintained with a thickness up to 35 nm. After storing in the glove box for 114 h, PDINN-TPA-based OSCs can exhibit excellent long-term stability (over 90 % of the optimal PCE). Besides, PDINN-P3P and PDINN-TPA were further utilized CILs in the PM6: BTP-eC9 system, and the PDINN-TPA-based OSCs acquired a PCE of 16.91 % (15.54 % for PDINN-P3P-based OSCs), highlighting the broad applicability of PDINN-P3P and PDINN-TPA. This study confirms that the synergistic effect of bay site modification and n-type self-doping on PDI can simultaneously optimize the thickness insensitivity and long-term stability of PDI-based CILs.

In‐Situ Removable Solid Additive Optimizing Active Layer and Cathode Interlayer of Organic Solar Cells

AbstractIn situ removable (ISR) solid additive can employ cold sublimation process to optimize active layer morphology for organic solar cells (OSCs), thus remaining unique potential. Herein, a feasible guideline is proposed to discover a new ISR solid additive 1‐bromo‐4‐chlorobenzene (CBB), whose removing time (TR) is between those of reported ISR solid additives 1,4‐dichlorobenzene (DCB) and 1‐chloro‐4‐iodobenzene (CIB). The CBB with a moderate TR is beneficial for affording the optimal active layer morphology and achieving the highest power conversion efficiency (PCE) of 18.58% for D18:L8‐BO binary active layer, as supported by the most efficient exciton splitting, the fastest exciton transfer, and the most balanced carrier transports. Due to the unique ISR ability, DCB, CBB, and CIB are further proposed to optimize the aggregation of PDINN cathode interlayer. Particularly, the CBB‐ and CIB‐treated PDINN interlayers afforded the D18:L8‐BO based binary OSCs with excellent PCEs of 19.38% and 19.26%, along with remarkable fill factors of 80.98% and 81.37%, respectively. The CBB‐ and CIB‐treated PDINN interlayers can suppress non‐radiative recombination of the devices, resulting in higher open‐circuit voltage. This work not only provides an effective approach to flourish ISR solid additives but also expands the application of the ISR solid additive in OSCs.

Photovoltaic enhancement in OSCs based on PM6:Y7 when doping the active layer with Ag2S nanoparticles

Herein, silver sulfide (Ag2S) nanoparticles (NPs) with an average size of 31 nm ± 4 nm were synthesized using a simple, economic, and eco-friendly method assisted by ultrasonic bathing; the reaction was carried out in a non-polluting aqueous medium. These Ag2S NPs were suspended in ethanol and used to dope the active layer of Organic Solar Cells (OSCs) based on PM6 (donor) and Y7 (acceptor) by adding 2 v/v % of a suspension to the PM6:Y7 solution in chlorobenzene (CB). The entire fabrication process and testing was carried out under normal atmospheric conditions. Field's metal (FM) was used as the top electrode of the OSCs, which is a eutectic alloy of bismuth, indium, and tin (Bi 32.5 %, In 51 %, and Sn 16.5 %) with a melting point above 62 °C deposited by free evaporation techniques. The average Power Conversion Efficiency (PCE) for the reference and doped OSCs were 9.19 % (9.43 % the best) and 10.31 % (10.77 % the best), respectively; representing an increase of more than 14 % in the PCE value when Ag2S NPs are added to the active layer. It can be attributed to different optical phenomena, among which could be the enhance in the internal light reflection processes (scattering) and the Local Surface Plasmon Resonance (LSPR) effect.

Exploring the potential of CsPbI3/CsPbBr3 heterojunction as an absorber layer in perovskite solar cells: a numerical and experimental study

Exploring the potential of CsPbI3/CsPbBr3 heterojunction as an absorber layer in perovskite solar cells: a numerical and experimental study

Current Status and Advances for Polymers in the Active Layer of Organic Solar Cells

Current Status and Advances for Polymers in the Active Layer of Organic Solar Cells

Scalable CIGS Solar Cells Employing a New Device Design of Nontoxic Buffer Layer and Microgrid Electrode.

The efficiency of copper indium gallium selenide (CIGS) solar cells that use transparent conductive oxide (TCO) as the top electrode decreases significantly as the device area increases owing to the poor electrical properties of TCO. Therefore, high-efficiency, large-area CIGS solar cells require the development of a novel top electrode with high transmittance and conductivity. In this study, a microgrid/TCO hybrid electrode is designed to minimize the optical and resistive losses that may occur in the top electrode of a CIGS solar cell. In addition, the buffer layer of the CIGS solar cells is changed from the conventional CdS buffer to a dry-processed wide-band gap ZnMgO (ZMO) buffer, resulting in increased device efficiency by minimizing parasitic absorption in the short-wavelength region. By optimizing the combination of ZMO buffer and the microgrid/TCO hybrid electrode, a device efficiency of up to 20.5% (with antireflection layers) is achieved over a small device area of 5 mm × 5 mm (total area). Moreover, CIGS solar cells with an increased device area of up to 20 mm × 70 mm (total area) exhibit an efficiency of up to 19.7% (with antireflection layers) when a microgrid/TCO hybrid electrode is applied. Thus, this study demonstrates the potential for high-efficiency, large-area CIGS solar cells with novel microgrid electrodes.

Fermi energy modulation by tellurium doping of thermoelectric copper(I) iodide

Copper(I) iodide (CuI) is the leading inorganic p-type transparent conductor, attracting major attention for its promising optoelectronic properties and facile growth methods, although, commercial uptake is limited due to its as-of-yet insufficient electrical conductivity. Doping CuI with the chalcogens (O, S, Se, Te) is a viable route to tune its electrical conductivity for applications such as in thin film transistors, hole transport layers in solar cells, and transparent thermoelectric generators. The heaviest chalcogen element, Te, is yet to be explored in heavily intrinsically p-type doped CuI at non-alloying concentrations, the subject of the present work. We report the effects of tellurium at the boundary between the doping and alloying regime (up to a maximum of 2.4 % Te) in CuI thin films and investigation the variation in the thermoelectric properties and electronic band structure of the material. Ion implanting tellurium into CuI led to a progressive reduction in the films' work functions from 4.9 eV to 4.5 eV while the ionization potential remained unchanged, measured through photoemission spectrometry. This signified a modulation of the Fermi energy relative to the valence band edge, having a major effect on the materials' electrical conductivity and Seebeck coefficient, the former decreasing by 3 orders of magnitude, while the latter increased by 80 %. We conducted density functional theory (DFT) calculations to elucidate the effect of tellurium doping on the band structure of CuI. Tellurium doping corroborated the shift of Fermi energy, the incorporation of impurity acceptor states deeper into the band gap, in addition to disordering the valence band maximum. This work shows that, the Fermi energy in heavily p-type doped CuI can be moved away from the valence band through Te doping in addition to introducing band disorder, useful for controlling the hosts’ transport properties.

Sequential Deposition of Diluted Aqueous SnO2 Dispersion for Perovskite Solar Cells

The widespread use of tin dioxide (SnO2) thin films as electron transport layer (ETL) of perovskite solar cells (PSCs) has been facilitated by commercial SnO2 nanocolloid dispersion. Nevertheless, challenges such as nanoparticle agglomeration have emerged, impacting film quality and interface properties critical for PSC performance. Herein, the efficacy of sequential, multistep spin‐coating of repeatedly diluted SnO2 aqueous suspension as a simple and effective approach to enhance ETL properties is explored. Through systematic experiments using dynamic light scattering, cyclic voltammetry, optical spectroscopy, and photoconductivity, it is demonstrated that the sequential deposition significantly improves the flatness and coverage of SnO2, leading to improved electron transport and transfer from a perovskite layer. Such a synergetic effect enables to fabricate lead iodide PSC (FAPbI3, FA: formamidinium) with a power conversion efficiency of 22.99% compared to 20.48% for the conventional 1‐step SnO2 layer. The findings underscore the potential of sequential SnO2 deposition as a promising technique for robust SnO2 films of photoelectric conversion devices.

Synergistically Modulating the Bay and Amid Sites of a Perylene Diimide Cathode Interface Layer for High-Efficiency and High-Stability Organic Solar Cells

Synergistically Modulating the <i>Bay and Amid</i> Sites of a Perylene Diimide Cathode Interface Layer for High-Efficiency and High-Stability Organic Solar Cells

Natural Chelating Agent-Treated Electron Transfer Layer for Friendly Environmental and Efficient Perovskite Solar Cells.

In perovskite solar cells (PSCs), the electron transfer layer (ETL) characteristics have significant effects on the photoelectric conversion efficiency (PCE) of the devices. Herein, a natural chelating agent polymer polyaspartic acid (PASP) is doped into the SnO2 precursor solution attributed to a strong interaction between PASP molecules and SnO2, which strengthens the interface contact and passivates the vacancy oxygen trap of the obtained SnO2 ETL, thus promoting the transfer of electrons. In addition, PASP can also regulate the growth of perovskite crystals, leading to an improved crystal quality of the perovskite films. Meanwhile, there is an excellent chelate anchoring of PASP to uncoordinated Pb2+, facilitating the reduction of trap defects at the interface, improving the stability of device, and suppressing the leakage of toxic Pb. Finally, the photovoltaic performance of the optimized device was greatly improved, and the PCE was increased from 21.22 to 23.49%, with outstanding environmental stability. This work provides an inexpensive and efficient treatment strategy that improves the performance and stability of friendly environmental PSCs.

Effects of Al2O3 Rear Interface Passivation on the Performance of Bifacial Kesterite‐Based Solar Cells with Fluorine‐Doped Tin Dioxide Back Contact

Herein, ultrathin Al2O3 is investigated as a rear interface passivation layer for kesterite solar cells with F:SnO2 (FTO) back contact for potential performance improvement. On the passivation layer, a thin Mo layer is deposited to improve the FTO's ohmicity. Further, NaF is evaporated on the copper zinc tin sulfide (CZTS) precursors to create openings at the passivation layer and achieve Na‐induced benefits in the absorber. The CZTS absorbers deposited directly on the Al2O3‐coated FTO peel off, while those with Mo interlayer do not. For pure sulfide kesterite devices, the Al2O3 layer reduces the short‐circuit current density (JSC), resulting in poor device efficiency. On the other hand, significantly higher JSC is realized for mixed sulfide and selenide kesterite devices with Al2O3 passivation layer, with the current density–voltage curve suggesting a reduced barrier height at the rear interface. As a result, the efficiency is improved from 1.5% for devices without Al2O3 to 4.6% for those with Al2O3. Likewise, improved external quantum efficiency response is observed in the devices with passivation layer for backside and frontside illumination. Therefore, contribution of Al2O3 passivation layer to the performance of kesterite‐based solar cells is evident from the results of this study.

Three-type precursors for low-temperature solution-processed void-and-crack-free copper(I) iodide films: comparison of electrical conductivities and optical transparency

Abstract Copper(I) iodide is a wide-bandgap (colorless) p-type semiconductor with a high Seebeck coefficient. Although copper(I) iodide is promising for fabricating transparent thermoelectric devices and hole-transfer layers of solar cells, the insolubility in common solvents due to 3-dimensional coordination networks has been a drawback to constructing low-temperature solution-processed thin films. Moreover, it is challenging to fabricate void-and-crack-free copper(I) iodide thin films through a convenient spin-coating process. In limited solvents of acetonitrile and diethyl sulfide, copper(I) iodide is dissolved by forming soluble copper(I) iodide complexes; however, void-and-crack-free copper(I) iodide thin films have never been prepared. In this study, we report that copper(I) iodide–alkanolamine complexes are soluble in alcohols and the spin-coated complexes undergo thermal decomposition to a copper(I) iodide thin film at moderately low temperatures until 150 °C. We discover that the copper(I) iodide–alkanolamines show different properties such as solubility and melting/decomposition temperatures depending on their structures. Specifically, by using 1-amino-2-propanol, we obtain void-and-crack-free and transparent copper(I) iodide thin films with controlled thicknesses of &amp;gt;50 nm. The conductivity, carrier density, mobility, and Seebeck coefficient of the copper(I) iodide thin film are 9.35 S·cm−1, 6.38 × 1019 cm−3, 0.96 cm2·V−1·S−1, and 192 µV·K−1, respectively.

Increased performance of A-DA’D-A type acceptor based organic solar cell using a thermally coevaporated cathode-modifying blend layer

The blend thin films of bathocuproine and fullerene (BCP:C60) have been thermally coevaporated to modify the active layer/cathode interfaces in organic solar cells. The BCP forms a much smaller-barrier contact with cathode than the C60. Because the surface zone of active layer is polymer donor-rich and small-molecular acceptor-deficient, C60 molecules make insufficiently large contact area with electron acceptor, leading to inefficient electron extraction. However, BCP molecules penetrate the surface of active layer, due to the smaller molecular size of BCP than that of C60, and likely form sufficiently large contact area with electron acceptor thereby to enable efficient electron extraction. Compared to conventional 10 nm BCP, 10 nm BCP:C60 (1:1 in mass ratio) enables higher efficiency based on the active layer using A-DA’D-A type acceptor, mostly because C60 constituent dissociates some excitons photogenerated in the polymer donor of surface zone and thereby increases short-circuit current density. The current research provides novel insights into the development of cathode-modifying layers for organic solar cells.

Anion and Cation Co-Doping of NiO for Transparent Photovoltaics and Smart Window Applications

Materials engineering based on metal oxides for manipulating the solar spectrum and producing solar energy have been under intense investigation over the last years. In this work, we present NiO thin films double doped with niobium (Nb) and nitrogen (N) as cation and anion dopants (NiO:(Nb,N)) to be used as p-type layers in all oxide transparent solar cells. The films were grown by sputtering a composite Ni-Nb target on room-temperature substrates in plasma containing 50% Ar, 25% O2, and 25% N2gases. The existence of Nb and N dopants in the NiO structure was confirmed by the Energy Dispersive X-Ray and X-Ray Photoelectron Spectroscopy techniques. The nominally undoped NiO film, which was deposited by sputtering a Ni target and used as the reference film, was oxygen-rich, single-phase cubic NiO, having a visible transmittance of less than 20%. Upon double doping with Nb and N the visible transmittance of NiO:(Nb,N) film increased to 60%, which was further improved after thermal treatment to around 85%. The respective values of the direct band gap in the undoped and double-doped films were 3.28 eV and 3.73 eV just after deposition, and 3.67 eV and 3.76 eV after thermal treatment. The changes in the properties of the films such as structural disorder, direct and indirect energy band gaps, Urbach tail states, and resistivity were correlated with the incorporation of Nb and N in their structure. The thermally treated NiO:(Nb,N) film was used to form a diode with a spin-coated two-layer, mesoporous on top of a compact, TiO2 film. The NiO:(Nb,N)/TiO2heterojunction exhibited visible transparency of around 80%, showed rectifying characteristics and the diode’s parameters were deduced using the I-V method. The diode revealed photovoltaic behavior upon illumination with UV light exhibiting a short circuit current density of 0.2 mA/cm2 and open-circuit voltage of 500 mV. Improvements of the output characteristics of the NiO:(Nb,N)/TiO2 UV-photovoltaic by proper engineering of the individual layers and device processing procedures are addressed. Transparent NiO:(Nb,N) films can be potential candidates in all-oxide ultraviolet photovoltaics for tandem solar cells, smart windows, and other optoelectronic devices.

Cu-Doped TiO2 Thin Films by Spin Coating: Investigation of Structural and Optical Properties

Cu-doped TiO2 films were synthesized directly on FTO glass with a spin coating method. With a variation in copper amount, samples were prepared with 0%, 1%, 2%, 4% and 8% of dopant concentrations. Morphological and structural characterization of undoped and Cu-doped TiO2 samples were investigated and the obtained results showed the small, spherical shapes of the nanoparticles forming a thin film on top of FTO glass and their preferred orientation of TiO2 anatase (101), which is the same for each sample. However, this peak exhibited a slight shift for the 2% sample, related to the inflation of the microstrain compared to the other samples. For the optical properties, the 4% sample displayed the highest transmittance whereas the 2% sample exhibited the lowest band gap energy of 2.96 eV. Moreover, the PL intensity seems to be at its highest for the 2% sample due to the present peaking defects in the structure, whereas the 8% sample shows a whole new signal that is related to copper oxide. These properties make this material a potential candidate to perform as an electron transport layer (ETL) in solar cells and enhance their power conversion efficiency.

Conformal zinc sulfide coating of vertically aligned ZnO nanorods by two-step hydrothermal synthesis on wide bandgap seed layers for lead-free perovskite solar cells

Vertically aligned ZnO nanorods (NRs) were grown hydrothermally on the wide bandgap (∼3.86 – 4.04 eV) seed layers (SLs) of grain size ∼162 ± 35 nm, prepared using ball-milled derived ZnO powder. The synthesized ZnO NRs were further decorated with ZnS nanocrystals to achieve a ZnO NR-ZnS core–shell (CS)-like nano-scaffolds by a subsequent hydrothermal synthesis at 70 °C for 1 h. UV-Vis-NIR spectroscopy, x-ray diffractometry (XRD), Raman spectroscopy and Field emission scanning electron microscopy (FESEM) coupled with Energy dispersive x-ray spectroscopy (EDX) analyses confirmed the formation of ZnS atop the vertically aligned ZnO NR arrays of ∼1.79 ± 0.17 µm length and ∼165 ± 27 nm diameter. Transmission electron microscopy (TEM)/EDX analyses revealed that vertically aligned ZnO NRs (core dia. ∼181 ± 12 nm) arrays are conformally coated by an ultrathin ZnS (∼25 ± 7 nm) shell layer with a preferential ZnS{111}/ZnO{10-10}-like partial epitaxy. The ZnO NRs exhibited a sharp band edge near ∼384 nm having optical bandgap energy (E g) of ∼3.23 eV. However, the ZnO NR-ZnS CS exhibited double absorption bands at E g ∼ 3.20 eV (ZnO-core) and E g ∼ 3.78 eV (ZnS-shell). The ZnS{111}/ZnO{10-10}-nano-scaffolds could be utilized to facilitate the enhanced absorption of UV photons as well as the radial junction formation between the Pb-free perovskite absorber and ZnS/ZnO NRs layers.