Promising Solar Absorber Research Articles

Structural Diversity in 2-(2-Aminoethyl)pyridine-Based Lead Iodide Hybrids.

While 2D metal-organic hybrids have emerged as promising solar absorbers due to their improved moisture stability, their inferior transport properties limit their potential translation into devices. We report a new hybrid containing 2-(2-ammonioethyl)pyridine [(2-AEP)+], forming a 2D hybrid with the composition (2-AEP)2PbI4. The organic bilayer comprises of (2-AEP)+, which is arranged in a face-to-face stacking that promotes π-π interactions between neighboring pyridyl rings. We also demonstrate the structural diversity of 2-(2-aminoethyl)pyridine-based lead iodide hybrids in solution-processed films. This report highlights the importance of solution-processing conditions in trying to obtain single-phase films of hybrids containing dibasic organic species.

Solution-Processed Sb2S3-Based Heterojunction for Self-Powered Broad Band Weak Light Detection.

Antimony sulfide (Sb2S3) has recently regained the attention of photovoltaic researchers as a promising solar absorber; however, its application for the detection of white light remains relatively unexplored. Herein, we report on the self-powered heterojunction photodetector based on a device-grade Sb2S3 film made at low temperature with solution processing. The Sb2S3 absorber film was prepared by single-step spin coating of a novel precursor ink using antimony trichloride as the antimony source along with the low melting thioacetamide as the sulfur source in 2-methoxyethanol, a low boiling environmentally friendly solvent. A simple TiO2/Sb2S3 heterojunction device made by using the film shows a power conversion efficiency of 1.22% without any hole transporting layer. Interestingly, the self-powered photodetector performance of the device under white light exhibits a high on/off ratio of 2.2 × 104 under 1 sun illumination. Moreover, this optical filter-free ultraviolet-visible absorbing near-infrared blind photodetector is equally capable of detecting both strong and weak white light, with a response time of 98 ms. Further, an example of the real-life application of the device is successfully demonstrated by constructing a weak light-detecting sunlight tracking system.

Optimization of a wavy-channel compact solar receiver with supercritical carbon dioxide

The compact solar receiver stands out as a promising solar absorber for the direct supercritical carbon dioxide cycle, and the wavy channel exhibits notable comprehensive performance owing to its excellent heat transfer capabilities and relatively low flow resistance. However, there exists considerable room for improvement in performance through the optimization of geometric parameters in wavy channels. In this paper, the amplitude and the period of the wavy channel are optimized by a coupled response surface method with multi-objective genetic algorithm, with objectives of maximizing the heat transfer coefficient and minimizing the friction factor. Results indicated that smaller period or larger amplitude enhances heat transfer but also increases flow resistance. Through the non-dominated sorting genetic algorithm and k-means clustering method, five representative optimal solutions were identified. The optimal result, characterized by a period of 15.07 mm and an amplitude of 1.73 mm, was selected based on the highest comprehensive heat transfer factor under identical pump power, reaching 1.213. This solution demonstrated high comprehensive performance across a wide range of working conditions. The optimization results are not only valuable for the design of compact solar receivers but also hold significant potential for application in other compact heat exchangers, such as printed circuit heat exchangers.

Carrier generation and collection in Zn3P2/InP heterojunction solar cells

Zinc phosphide (Zn3P2) has been lauded as a promising solar absorber material due to its functional properties and the abundance of zinc and phosphorous. In the last 4 decades, there has not been any significant improvement in the efficiencies of Zn3P2-based solar cells. This is vastly due to the limited understanding of how to tune its optoelectronic properties. Recently, significant progress has been made in the growth and characterization of the material, which has shed light on its potential. In this study, we report an energy conversion efficiency as high as 4.4% for a solar cell based on a polycrystalline Zn3P2/InP heterojunction. This device presents an open circuit voltage of 528.8 mV, 7.5% higher than the Zn3P2 homojunction record. We investigate the dominant recombination mechanisms within the film using different techniques to identify the key factors underpinning our device efficiency. In particular, we pinpoint that reduced carrier collection at the front of Zn3P2 is responsible for the reduced collection of high-energy photons. This allows us to suggest the design rules for next-generation Zn3P2-based heterojunction solar cells, which should allow us to go beyond the current conversion values.

Thermally Deposited Sb2Se3/CdS-Based Solar Cell: Experimental and Theoretical Analysis.

As a promising solar absorber material, antimony selenide (Sb2Se3) has gained popularity. However, a lack of knowledge regarding material and device physics has slowed the rapid growth of Sb2Se3-based devices. This study compares the experimental and computational analysis of the photovoltaic performance of Sb2Se3-/CdS-based solar cells. We construct a specific device that may be produced in any lab using the thermal evaporation technique. Experimentally, efficiency is improved from 0.96% to 1.36% by varying the absorber's thickness. Experimental information on Sb2Se3, such as the band gap and thickness, is used in the simulation to check the performance of the device after the optimization of various other parameters, including the series and shunt resistance, and a theoretical maximum efficiency of 4.42% is achieved. Further, the device's efficiency is improved to 11.27% by optimizing the various parameters of the active layer. It thus is demonstrated that the band gap and thickness of active layers strongly affect the overall performance of a photovoltaic device.

Cu2SiSe3 as a promising solar absorber: harnessing cation dissimilarity to avoid killer antisites

Cu2SiSe3 as a promising solar absorber: harnessing cation dissimilarity to avoid killer antisites

Two-dimensional Ruddlesden-Popper halide perovskite solar absorbers with short-chain interlayer spacers

Two-dimensional Ruddlesden-Popper (2DRP) halide perovskites have emerged as promising solar absorbers due to their much-enhanced stability compared with their three-dimensional counterparts, but the light conversion efficiency is limited by their intrinsic optoelectronic properties such as increased exciton binding energy and poor cross-layer carrier transport properties. We herein demonstrate, through first-principles calculations, that the efficiency of 2DRP halide perovskites can be enhanced by adopting the short-chain interlayer spacers among perovskite layers. We adopted short-chain alkylmethylammonium (MA) and formamidinium (FA) organic cations to exchange the regular long-chain butylammonium (BA) and phenethylammonium (PEA) cations in 2DRP halide perovskites with the formula ${A}_{2}B{\mathrm{Pb}}_{2}{\mathrm{I}}_{7}$ ($A=\mathrm{BA}$, PEA, MA, and FA; $B=\mathrm{MA}$ and FA). We find that varying the interlayer spacers results in changed distortion of ${\mathrm{PbI}}_{6}$ octahedra of the perovskite framework, which in turn influences the stability and electronic structure of 2DRP perovskites. Compared with the long-chain BA/PEA intercalated 2DRP perovskites, the short-chain MA/FA intercalated ones have slightly reduced thermodynamic stability, but their calculated bandgaps are closer to the ideal value for solar cells (1.3--1.6 eV), accompanied with comparable carrier effective masses and optical absorption. More importantly, they demonstrate lower exciton binding energies and two orders of magnitude increased out-of-plane carrier tunneling probability. These factors are expected to further enhance the power conversion efficiency of 2DRP-based solar cells.

Metal-ceramic carbide integrated solar-driven evaporation device based on ZrC nanoparticles for water evaporation and desalination

Due to the superior characteristics of strong localized surface plasmon resonance, low-cost consumption, and substantial chemical and thermal stability, conductive metal-ceramic nitrides, such as TiN, ZrN and HfN, are considered promising photothermal materials for solar-driven water evaporation and desalination. Transition metal carbides have also been proposed as promising solar absorbers, making them suitable candidates for solar-driven interfacial evaporation and desalination. However, little attention has been paid to this aspect thus far. Here, to gain new insights into the evaporation and desalination performance, we chose ZrC nanoparticles (NPs) as the experimental subject to fabricate an interfacial evaporation device. The highest evaporation rate and evaporation efficiency values were 1.43 ± 0.04 kg m−2 and 98 ± 2%, respectively, for the ZrC NP-integrated device at a loading mass of 85 g/m2. Desalination was further tested using simulated water (3.5% salinity) and collected saline water (21% salinity) as sources, and the evaporation rate and efficiency reached 1.38 ± 0.1 kg m−2 h−1 and 96 ± 0.75%, respectively, under 1 sun illumination. Measurement of ion concentrations following the desalination process demonstrates the effective removal of major saline ions (Na+, Mg2+, K+ and Ca2+).

Efficient Sb2(S,Se)3 Solar Modules Enabled by Hydrothermal Deposition

Antimony selenosulfide (Sb2(S,Se)3) is a promising solar absorber due to the excellent stability and suitable photovoltaic parameters. The power conversion efficiency (PCE) has overcome 10% in lab scale. In terms of practical applications, the efficiency should be further improved and the suitable scalable fabrication approach should also be established. Herein, a large‐area fabrication of Sb2(S,Se)3 solar cell by hydrothermal deposition is demonstrated. It is found that this approach is able to generate Sb2(S,Se)3 film with high uniformity with regard to both the chemical composition and surface morphology. Taking advantage of laser scribing technology, series connected antimony selenosulfide monolithic integrated photovoltaic modules are obtained. The prepared solar cell achieved PCE of 7.43%, with an active area of 15.66 cm2, which is the highest efficiency at module scale. A convenient approach for the fabrication of large‐area series‐connected Sb2(S,Se)3 solar cells is offered.

(Li,Na)SbS2 as a promising solar absorber material: A theoretical investigation

NaSbS2 has been proposed as a novel photovoltaic material, but its band gap is not suitable for single-junction solar cells. In the present study, the systematic first-principles calculations were carried out to investigate the structural, mechanical, electronic and optical properties of ASbS2 (A = Li, Na, K) and Na1-xLixSbS2 solid solutions. These structures show good structural stability compared to CH3NH3PbI3. The results indicate that all the structures are indirect band gap semiconductors. The band gap of ASbS2 increases gradually when the alkali metal changes from Li to K. The band gap of NaSbS2 can be tuned by manipulating the amount of Li doping. The Na1-xLixSbS2 solid solutions have suitable band gaps for light-absorber semiconductors in solar cells. Moreover, the suitable band gap of NaSbS2 can be also obtained under moderate pressure. The mechanical properties of these materials are also analyzed, and the results indicate that they are brittle materials except for KSbS2. The optical absorption coefficients of these compounds are large over 10−5 cm−1 in the visible light region. We find that alloying can provide a feasible and effective approach for improving the photovoltaic performance of NaSbS2-based solar cells.

Over 7% Efficiency of Sb2(S,Se)3 Solar Cells via V‐Shaped Bandgap Engineering

Antimony chalcogenides (including Sb2S3, Sb2Se3, and Sb2(S,Se)3 alloy) have emerged as promising solar absorber materials. Notably, the Sb2(S,Se)3 alloy possesses continuously tunable bandgap from 1.1 to 1.7 eV, which covers the ideal bandgap for single‐junction photovoltaics governed by the Shockley–Queisser theory. Moreover, the bandgap gradient provides effective ways for photogenerated carriers collection and has the potential for high‐efficient Sb2(S,Se)3 alloy solar cells. Herein, a V‐shaped distributional bandgap in Sb2(S,Se)3 solar cells is reported through a simple dual‐source vapor transport deposition process, enabling the synergetic increase of the open‐circuit voltage (VOC) and short‐circuit current (JSC). Through careful optimization, a power conversion efficiency of 7.27% under AM1.5G illumination is obtained, with VOC and JSC of 0.46 V and 29.6 mA cm−2, respectively. This V‐shaped bandgap engineering provides an effective method to enhance the device performance and can be extended to other chalcogenide thin‐film solar cells such as Sn–X, Ge–X, Cu–Sb–X (X = S and Se), and so on.

Heterogeneous electron transporting layer for reproducible, efficient and stable planar perovskite solar cells

Organometal-halide perovskites continue to attract a large number of solar enthusiasts due to their intrinsic properties as promising solar absorbers with relatively low processing cost. However, commercialization of perovskite solar cells remains distant, especially in the planar perovskite configuration, because of various problems such as inconsistency, poor environmental stability, and small-scale production. In this study, we present the use of complimentary electron transporting layers (ETLs) as a highly effective approach to cover the weaknesses of individual ETLs while boosting the strengths of various ETL compositions. Heterogeneous AITO/SnO2 ETL based device demonstrates paramount efficiency of 18.90% and exhibits superior stability maintaining 93% of its initial efficiency after 25 days in the absence of encapsulation at relative humidity of 30–40%. Furthermore, the simple addition of a consistent AITO layer allows improvement in reproducibility, while the simple addition of a SnO2 layer exhibits significant enhancement in electron mobility and reduction in recombination sites at the AITO/perovskite interface. In essence, our results suggest the use of compatible heterogeneous ETLs as an appealing method to provide synergistic enhancements in various photovoltaic parameters, device stability, and also device reproducibility of planar perovskite devices.

Suitable junction partners for promising solar absorbers

Screening for optimal electronic band offsets and low strain identifies four partner materials that merit future study.

The complex defect chemistry of antimony selenide

Sb2Se3 is a highly promising solar absorber material, however a comprehensive study of its intrinsic defects finds multiple deep transition levels within the gap that could limit open circuit voltages of cells.

Machine learning the band gap properties of kesterite I2−II−IV−V4 quaternary compounds for photovoltaics applications

Kesterite I$_2$-II-IV-V$_4$ semiconductors are promising solar absorbers for photovoltaics applications. The band gap and it's character, either direct or indirect, are fundamental properties determining photovoltaic-device efficiency. We use a combination of accurate first-principles calculations and machine learning to predict the properties of the band gap for a large number of kesterite I$_2$-II-IV-V$_4$ semiconductors. In determining the magnitude of the fundamental gap, we compare results for a number of machine-learning models, and achieve a root mean squared error as low as 283 meV; the best results are achieved using support-vector regression with a radial-bias kernel. This error is well within the uncertainty of even the most advanced first-principles methods for calculating semiconductor band gaps. Predicting the direct--indirect property of the band gap is more challenging. After significant feature engineering, we are able to train a classifier that predicts the nature of the band gap with an accuracy of 89 \% using logistic regression. Using these trained models, the band gap properties of 1568 kesterite I$_2$-II-IV-V$_4$ compounds are predicted. We find 717 compounds with band gaps in the range 0.5 -- 2.5 eV that can potentially act as solar absorbers, and 242 materials with a band gap in the ``\emph{optimum range}" of 1.2 -- 1.8 eV. The stability of these 242 compounds is assessed by calculating the Energy Above Hull using the Materials Project database, and the band gaps are verified using hybrid functional calculations; in the end, we identify 25 compounds that are expected to be synthesizable, and have a band gap in the range 1.2 -- 1.8 eV -- most of which are previously unexplored. These results will be useful in the materials engineering of efficient photovoltaic devices.

Sonochemical synthesis of CuIn0.7Ga0.3Se2 nanoparticles for thin film photo absorber application

CuInGaSe2 (CIGS) has been considered as promising solar absorber material for thin film solar cells leading to efficiencies exceeding 22% on lab scale. CIGS thin film solar cells fabricated from CIGS nanoparticles (NPs) inks by nonvacuum techniques is essential for cost effective cell fabrication process and for upscaling. In this regard, one step sonochemical synthesis of CIGS NPs employing relatively non-toxic precursors of metallic salts and selenourea in an aqueous medium under ambient conditions is being presented. Precursor ratios and sonication time were optimized to realize high-quality chalcopyrite crystal phases of CIGS NPs obtained by sonochemical route. X ray diffraction, UV–vis–NIR, Raman, Energy dispersive spectroscopy and Transmission electron microscopy confirmed the formation of tetragonal chalcopyrite CIGS NPs with a band gap of 1.42 eV and NPs size of about 20 nm.

Recycled waste black polyurethane sponges for solar vapor generation and distillation

The abundant waste polyurethane sponge, commonly considered as one of the municipal wastes, can be recycled and converted into the valuable resources of environment. The increasing landfill cost and air-pollutions have made it a great urgent to develop the effective applications of waste polyurethane sponge. Recently, solar vapor generation has attracted extensive attentions, since energy shortage and water scarcity along with water pollution are becoming alarming global issues to be addressed. The solar vapor generation relies on the performance of the solar absorbers which convert the solar energy into heat for the vaporization process. A low cost, efficient and durable solar absorber is vital for the development of solar vapor generation. Here, we report that the recycled self-floating black polyurethane sponges are very promising solar absorber materials. which can efficiently generate water vapor after a simple one-step hydrophilic treatment with dopamine hydrochloride. The evaporating rate was more than 3.5 times higher compared to that of the existing natural evaporation process, exhibiting an evaporation efficiency of above 50%. Furthermore, this black polyurethane sponge can also drive solar ethanol distillation, yielding up to 25wt% concentration promotion under each distillation cycle.

Influence of an interfacial cesium oxide thin layer in the performance and internal dynamic processes of GaSe9 solar cells

Solar cells based on evaporated Cs2O/GaSe9 and Cs2O/Se (as comparison) active layers have been investigated. We correlate their performance with devices previously reported without Cs2O. GaSe9 appears as a very promising solar absorber because of its attractive optical and electrical properties. We improved device performance by around 30% by inserting a Cs2O thin interlayer. Current density-voltage, capacitance-voltage and impedance spectroscopy measurements were used to characterize the effect of Cs2O layer on device performance. The charge carrier concentration and the built-in potential were derived using Schottky-Mott relation. The enhancement promoted by Cs2O is attributed to an improvement in electron extraction efficiency by FTO, and the avoidance of Se sublimation during the annealing process. The insertion of the metallic oxide also increases the built-in potential at FTO/GaSe9 interface. Dynamic processes were clearly identified by impedance spectroscopy under complex modulus analysis, confirming better capabilities of charge collection by the Cs2O containing electrodes.

Single-step organic vapor phase sulfurization synthesis of p-SnS photo-absorber for graded band-gap thin film heterojunction solar cells with n-ZnO1-x Sx

Tin sulfide has emerged as a promising solar absorber among the IV-VI binary compound which is earth-abundant and non-toxic. This research provides a new perspective on synthesis of photosensitive monophasic SnS films by organic chemical vapor sulfurization of Sn thin film. S-radicals formed by closed space pyrolysis of di-tert-butyl disulfide (TBDS) diffusively react with Sn to produce SnS film. SnS being an amphoteric semiconductor converts to n-type by trivalent Sb and Bi dopants. The organic vapor sulfurization method described in this research facilitates single-step synthesis of buried junction structures and thus SnS solar cells in a p-n homojunction or p-i-n structures. In this work, vacuum evaporated Sn thin film with a thickness of 100 nm, was converted to SnS by sulfurization under 100 sccm flow of TBDS vapor preheated to 100°C and structural phase evolution and film growth kinetics were investigated for sulfurization at 200°C, 300°C and 400°C for a periods 90 min. X-ray diffraction studies establish single phase highly crystalline film in orthorhombic crystal structure forms at 200°C. Raman scattering results confirm SnS formation with the identification of 2Ag, 2B2g optical phonons modes. Optical bandgap studies confirm a low energy 1.1-1.4 eV indirect bandgap and a strong absorption threshold between 1.4 to 1.6 eV direct band gap depending on the sulfurization conditions correlating with intrinsic defects and phase structure of the film.

One-step sonochemical synthesis route towards kesterite Cu2ZnSnS4 nanoparticles

Cu2ZnSnS4 (CZTS) has been considered as one of the most promising solar absorber in low-cost high-efficiency thin-film solar cells, which can be produced from CZTS nanoparticles (NPs) inks by non-vacuum fabrication techniques such as the roll-to-roll process. In this paper, one-step sonochemical synthesis towards the CZTS NPs at room temperature was studied. In the synthesis, the sonication time and the precursor’s concentration were two important factors to affect the crystal phases of the resulting NPs. Following analyses of X-ray diffraction, UV–Vis–NIR and Raman spectroscopy, high-resolution transmission electron microscopy and scanning electron microscopy with energy dispersive X-ray spectrometry, the kesterite CZTS nanocrystals with the average NP size ∼2nm and the band gap ∼1.52eV could be obtained with suitable precursor’s concentration and sonication time.