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Earth‐abundant and environmentally benign kesterite Cu2ZnSn(S,Se)4 (CZTSSe) is a promising alternative to its cousin chalcopyrite Cu(In,Ga)(S,Se)2 (CIGS) for photovoltaic applications. However, the power conversion efficiency of CZTSSe solar cells has been stagnant at 12.6% for years, still far lower than that of CIGS (23.35%). In this report, insights into the latest cutting‐edge strategies for further advance in the performance of kesterite solar cells is provided, particularly focusing on the postdeposition thermal treatment (for bare absorber, heterojunction, and completed device), alkali doping, and bandgap grading by engineering graded cation and/or anion alloying. These strategies, which have led to the step‐change improvements in the power conversion efficiency of the counterpart CIGS solar cells, are also the most promising ones to achieve further efficiency breakthroughs for kesterite solar cells. Herein, the recent advances in kesterite solar cells along these pathways are reviewed, and more importantly, a comprehensive understanding of the underlying mechanisms is provided, and promising directions for the ongoing development of kesterite solar cells are proposed. [ABSTRACT FROM AUTHOR]

Lithium incorporation in kesterite Cu2ZnSn(S,Se)4 (CZTSSe) materials has been experimentally proven effective in improving electronic quality for application in photovoltaic devices. Herein, a feasible and effective solution‐based lithium post‐deposition treatment (PDT), enabling further efficiency improvement on the high‐performance baseline is reported and the dominant mechanism for this improvement is proposed. In this way, lithium is uniformly incorporated into grain interiors (GIs) without segregation at grain boundaries (GBs), which can occupy the Zn sites with a high solubility in the CZTSSe matrix, producing high density of LiZn antisites with shallower acceptor levels than the intrinsic dominant defect (CuZn antisites). As a result, CZTSSe absorber with better p‐type doping is obtained, leading to a pronounced enhancement in fill factor and a corresponding gain in open‐circuit voltage and short‐circuit current and consequently a significant efficiency boost from 9.3% to 10.7%. This work provides a feasible alternative alkali‐PDT treatment for chalcogenide semiconductors and promotes a better understanding of the mechanism of Li incorporation in kesterite materials. [ABSTRACT FROM AUTHOR]

Majority carrier mobility is one of the most fundamental and yet important carrier transport parameters determining the optimal device architecture and performance of the emerging antimony chalcogenide solar cells. However, carrier mobility measurements based on the Hall effect have limitations for these highly anisotropy materials due to the discrepancy of transport directions under Hall measurement and device operation. Herein, a defect‐resolved mobility measurement (DRMM) method enabling the evaluation of effective majority carrier mobility from a working device without such limitations is presented. Using this method, comprehensive information about the carrier transport in representative Sb2S3 and Sb2Se3 solar cells is extracted. Though with preferred [hk1]‐crystalline orientation, Sb2S3 and Sb2Se3 still suffer from extremely low carrier mobility and low carrier density, respectively, resulting in large bulk resistance and poor carrier collection efficiency. Further crystalline structure analysis discloses that crystalline defects such as dislocations may significantly constrain carrier transport in these low‐dimensional materials. These results suggest that a p‐i‐n device architecture with fully depleted absorber is a promising optimization approach for further efficiency advances of antimony chalcogenide solar cells. [ABSTRACT FROM AUTHOR]

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since June 2020 are reviewed. In this issue, charts showing efficiency improvements since 1993 are included as well as cell and module area definitions and an updated list of recognized test centres. [ABSTRACT FROM AUTHOR]

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since January 2020 are reviewed. [ABSTRACT FROM AUTHOR]

A proof‐of‐concept tandem solar cell using Sb2S3 and Sb2Se3 as top and bottom cell absorber materials is demonstrated. The bandgaps of Sb2S3 and Sb2Se3 are 1.74 and 1.22 eV, perfectly satisfying the requirement of tandem solar cells. The application of few‐layer graphene enables high transmittance and excellent interfacial contact in the top subcell. By controlling the thickness of the top cell for maximizing the spectral application, the tandem device delivers a power conversion efficiency of 7.93%, which outperforms the individually optimized top cell (5.58%) and bottom cell (6.50%). Mechanistical investigation shows that the tandem device is able to make up voltage loss in the subcells, which is a critical concern in the current antimony chalcogenide solar cells. This study provides an alternative approach to enhancing the energy conversion efficiency of antimony selenosulfide. [ABSTRACT FROM AUTHOR]

an important step towards the realisation of silicon-based tandem solar cells using silicon quantum dots embedded in a silicon dioxide (SiO) matrix, single-junction silicon quantum dot (Si QD) solar cells on quartz substrates have been fabricated. The total thickness of the solar cell material is 420 nm. The cells contain 4 nm diameter Si quantum dots. The impacts of post-metallisation treatments such as phosphoric acid (HPO) etching, nitrogen (N) gas anneal and forming gas (Ar: H) anneal on the cells' electrical and photovoltaic properties are investigated. The Si QD solar cells studied in this work have achieved an open circuit voltage of 410 mV after various processes. Parameters extracted from dark I- V, light I- V and circular transfer length measurement (CTLM) suggest limiting mechanism in the Si QD solar cell operation and possible approaches for further improvement. [ABSTRACT FROM AUTHOR]

The article explores how the metal oxide buffer material is commonly used to protect the organic hole transporting layer from damage due to sputtering of the transparent conducting oxide, and Inorganic–organic hybrid perovskite solar cells (PSCs) have rapidly developed within a decade starting off with power conversion efficiencies (PCEs). It mentions improvement of silicon solar cell efficiencies through siliconperovskite tandems is realistic business models.

Antimony sulfide (Sb2S3) as a wide‐bandgap, nontoxic, and stable photovoltaic material reveals great potential for the uppermost cells in Si‐based tandem cell stacks. Sb2S3 solar cells with a compatible process, acceptable cost, and high efficiency therefore become the mandatory prerequisites to match silicon bottom cells. The performance of vacuum processed Sb2S3 device is pinned by bulk and interfacial recombination. Herein, a thermally treated TiO2 buffer layer induces quasiepitaxial growth of vertical orientation Sb2S3 absorber overcoming interface defects and absorber transport loss. Such novel growth could pronouncedly improve the open‐circuit voltage (Voc) due to the superior interface quality and intraribbon transport. The epitaxial rough Sb2S3 surface shows a texturized‐like morphology. It is optimized by tuning the grain sizes to form strong light trapping effect, which further enhances the short‐circuit current density (Jsc) with a 16% improvement. The final optimal device with high stability obtains a power conversion efficiency of 5.4%, which is the best efficiency for full‐inorganic Sb2S3 solar cells. The present developed quasiepitaxy strategy supports a superior interface, vertical orientation, and surface light trapping effect, which provides a new perspective for efficient noncubic material thin film solar cells. [ABSTRACT FROM AUTHOR]

• Preparation of CZTS thin films via facile and environmentally friendly SILAR method. • Analysis of the effects of different annealing temperature and holding time on film quality. • Fabrication of 4.26% efficiency solar cells by water-based inorganic method. Kesterite Cu 2 ZnSnS 4 (CZTS) solar cells are regarded as a promising photovoltaic technology owing to the non-toxic and earth-abundant constitutes. With the application of scalable and low-cost solution methods, the possibility of its commercialization can be further increased. This work explores preparing prominent CZTS films by an economically feasible successive ionic adsorption and reaction (SILAR) synthesis method. The obtained precursor with the Mo/ZnS/Cu 2 SnS 3 structure requires appropriate substantial annealing under a chalcogen atmosphere to form kesterite CZTS films. The annealing process is therefore optimized to improve the film quality and the performance of solar cells. Specifically, the optimal annealing condition is determined by adjusting the annealing temperature and holding time, respectively. The CZTS film annealed at 580 °C for 60 min demonstrates better film quality in terms of surface morphology, crystallinity, and phase purity. Consequently, CZTS solar cells fabricated with the optimal absorber exhibit a preferable efficiency of up to 4.26%. [ABSTRACT FROM AUTHOR]

Among various thin-film solar cell absorber materials, the kesterite semiconductor Cu SB 2 sb ZnSn(S, Se) SB 4 sb (CZTSSe) is composed of earth-abundant and environmental-friendly elements while possessing promising optical-electrical properties. This leads to a short minority carrier lifetime and diffusion length in CZTSSe solar cells, which is almost one order of magnitude lower than that in CdTe, CIGSe and perovskite, let alone silicon solar cells. However, the low critical temperature of Cu and Zn position replacement in CZTSSe implies that the influence of the significant amount of Cu-Zn disorder cannot be eliminated during the study of other defects/defect clusters. Massive Cu-Zn antisite defects in the bulk of CZTSSe result from nearly the same cation sizes as well as small chemical mismatch of Cu SP + sp and Zn SP + sp . [Extracted from the article]

Highlights • Cu 2 ZnSnS 4 thin films are fabricated on Si substrates by one-step sputtering. • Cu 2 ZnSnS 4 solar cells on Si with photovoltaic response are fabricated. • The interactions between Cu 2 ZnSnS 4 and Si are studied. Abstract Integrating commercialized Si solar cells with eco-friendly and earth-abundant Cu 2 ZnSnS 4 (CZTS) film is a promising method to increase power conversion efficiency and hence reduce the levelized cost of electricity. However, synthesis of CZTS thin film on Si as well as the study of the interaction between the two materials, which are crucial for good performance of CZTS/Si two-terminal devices, are areas that have been less investigated. Here, we grow polycrystalline CZTS thin films on Si (1 0 0) substrate by sputtering and study the properties of the CZTS thin film and interface between the CZTS and Si. The CZTS shows uniform microstructure and optimal optical properties. A CZTS solar cell which is fabricated on Si shows a photovoltaic response although subjected to high serious resistance, and Cu diffusion was found from CZTS into Si, which caused needle-like dislocations in Si. Therefore, an effective conductive barrier layer between CZTS and Si is desirable to inhibit Cu from diffusing into Si for tandem solar cell purposes. The study offers valuable input for understanding the properties of CZTS thin film sputtered from single target sputtering and the impact on the interfaces and underlying Si, suggesting concerns that manufacturers need to be aware of for its application in tandem solar cells based on Si. [ABSTRACT FROM AUTHOR]

• Effect of reflect coating on the SRT performance was tested for the first time. • A temperature reduction of 10–11 °C was observed in the lab and field tests. • Electrical efficiency improvement of 6.61 % was achieved with the application of RC. • A decrease in internal test chamber temperature of 18.7 % could be attained with RC. Compared to solar panels, the current adoption rate of building integrated photovoltaic (BIPV) systems in Australia is relatively low owing to their complex design, fluctuation in efficiency during operation and high cost. The efficiency of the BIPV system drops significantly with the increase of module temperature beyond 25°C. To stabilise the system temperature during operation and reduce the complexity of integration of a cooling system, reflective coating (RC) has been introduced in the present work. The effect of reflective coating on the electrical and thermal performances of a BIPV system, specifically solar roof tiles (SRTs), has been investigated. Several types of RCs and their application methods have been tested to optimise their performance. In the laboratory test, it was found that the RC could reduce the surface temperature by 11 °C, leading to an electrical efficiency improvement of 6.61%; while in the natural environment test, the observed temperature reduction was 10 °C, providing an electrical efficiency improvement of 6%. The internal temperature of an enclosed polystyrene test chamber placed under the SRTs during testing was also monitored. It was found that a reduction in the internal test chamber temperature of 18.7% could be achieved with RC, indicating a positive influence in lowering the interference between indoor and outdoor environments. However, RC beneath the monocrystalline silicon solar cells did not make an obvious contribution to the temperature reduction. [ABSTRACT FROM AUTHOR]

Perovskite solar cells (PSCs) have now achieved power conversion efficiencies (PCEs) over 25%, but their long-term stability under illumination and thermal stress is still a major barrier to commercialisation. Herein, we demonstrate the evaluation of light-induced degradation activation energy (E a) of encapsulated semi-transparent PSCs by using the commonly employed method in crystalline silicon solar cells. Different parameters showed different activation energies where primary degradation is due to increase in series resistance, which also led to reduction in short-circuit current. Open-circuit voltage and shunt resistance also change with different E a , suggesting the mechanism of the reduction is likely to be due to different reasons. Despite each parameter exhibiting slight variation over time for each temperature, the overall trend converges, indicating that each parameter is likely to be primarily reduced by a single dominant reaction. We also report the main cause of irreversible device degradation is not due to the decomposition of the perovskite layer as confirmed by X-ray diffraction characterisation. Instead, our pole figure map and absorption spectra analysis indicate that a loss of crystal symmetry occurs due to ion migration within the device that induce oxidation of 2,2′,7,7′-tetrakis-(N , N -di-4-methoxyphenylamino)-9,9′-spirobifluorene (Spiro-OMeTAD). Our work provides a better understanding through quantification of the degradation processes of encapsulated semi-transparent PSCs over time, which is essential for further progress and development of stable perovskite-Si tandem solar cells. • The light-induced degradation in semi-transparent solar cell is investigated. • The primary loss of PCEs in PSCs was due to an increase in series resistance. • XRD results indicate stability of perovskite layer, with degradation occurring in other layers. • Diffusion of ions back into the perovskite layer results in a recovery from LID. [ABSTRACT FROM AUTHOR]