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Solution processability is a prominent advantage for the commercial fabrication of perovskite solar cells (PSCs). However, ionic side reactions can cause perovskite solutions to age, which greatly limits the industrial prospects for reproducible production of PSCs. Herein, the mechanism of underlying halogen anion side reactions is elucidated and an effective scheme for managing halogen anions is proposed. The oxidation of halogen anions is the main factor of solution aging. The addition of iodine monobromide (IBr) stabilizes the precursor solution by promoting the reverse oxidation reaction. Meanwhile, IBr can manage the loss of halogen anion in perovskite layers, effectively reducing the defect density. Moreover, IBr can improve the crystallization process to prepare perovskite films with large‐sized grains and high crystallinity. As a result, the IBr‐based perovskite solution can be stored for 14 days, the optimal device efficiency (24.05% at 0.09 cm2) and long‐term operational stability are far superior to control samples. By this strategy, a large‐area perovskite solar module with an efficiency of 19.34% is fabricated on the 6 × 6 cm2 substrate. This study is dedicated to providing a strategy for managing halogen anions to inhibit solution aging and improve film quality. [ABSTRACT FROM AUTHOR]

Metamaterial absorbers have become a popular research direction due to their broad application prospects, such as in radar, infrared imaging, and solar cell fields. Usually, nanostructured metamaterials are associated with a large number of geometric parameters, and traditional simulation designs are time consuming. In this paper, we propose a framework for designing plasma metamaterial absorbers in both a forward prediction and inverse design composed of a primary prediction network (PPN) and an auxiliary prediction network (APN). The framework can build the relationship between the geometric parameters of metamaterials and their optical response (reflection spectra, absorption spectra) from a large number of training samples, thus solving the problem of time-consuming and case-by-case numerical simulations in traditional metamaterial design. This framework can not only improve forward prediction more accurately and efficiently but also inverse design metamaterial absorbers from a given required optical response. It was verified that it is also applicable to absorbers of different structures and materials. Our results show that it can be used in metamaterial absorbers, chiral metamaterials, metamaterial filters, and other fields. [ABSTRACT FROM AUTHOR]

The nucleation and crystallization processes within solution‐processed deposition is key for obtaining perovskite films with high quality. Herein, the synergistic effect of Cs+, ligand solvent (tetramethylene sulfoxide, TMSO), and methylammonium ions (MA+) on nucleation and crystallization procedures of preparing perovskites films is studied. The results reveal that producing α‐phase nuclei in the intermediate‐phase film (a perovskite film formed by removing the solvent before annealing) is the key factor for obtaining α‐phase‐pure perovskites, wherein Cs+ is necessary for reducing the formation energy of the α‐phase. In addition, the nonvolatile ligand (TMSO) is used to inhibit rapid nucleation, because it can form a stable intermediate phase. Furthermore, the introduction of the volatile MA+ cations compound (MACl) combined with Cs+ contributed to the direct formation of α‐phase nuclei in the intermediate‐phase film, and ion exchange (between FA+ and MA+) occurs during the subsequent annealing process, which leads to the formation of large‐grain perovskite film with good crystallinity. Maximum power conversion efficiencies of 22.08% and 16.88% are obtained via this strategy for a perovskite solar cell on a small area (active area: 0.09 cm2) and a perovskite solar module (aperture area: 12.92 cm2), respectively. [ABSTRACT FROM AUTHOR]

The incorporation of various cations and halides to form mixed perovskites has enabled perovskite solar cells (PSCs) to exceed 20% power conversion efficiencies (PCEs). However, they are primarily prepared by solution methods, which limit film uniformity and scalability. Although co‐evaporation is used to prepare all‐vacuum‐deposited PSCs with a decent performance, it involves multiple sources and quartz crystal monitors (QCMs) to simultaneously control deposition rates and film thicknesses, which increase production cost and fabrication complexity and interfere QCMs' reading precision. Herein, a simple and cost‐effective sequential vapor deposition involving only one QCM and two sources is demonstrated as an advantageous and reliable method to fabricate high‐quality and uniform mixed‐cation mixed‐halide perovskite films with microscale grain sizes and extraordinary morphology for the PSC application. In addition, for the first time, radio frequency (RF)‐sputtered SnO2 is implemented into all‐vacuum‐deposited PSCs as an electron transport layer (ETL). Together with evaporated copper phthalocyanine (CuPc) as a thermally and chemically stable low‐cost hole transport layer (HTL), alternative to the commonly used 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamino)‐9,9′‐spirobifluorene (Spiro‐OMeTAD), which is costly, highly hygroscopic, and deliquescent, a respectable PCE of 15.14% is achieved with a promising device stability and negligible hysteresis. [ABSTRACT FROM AUTHOR]

Organometallic trihalide perovskites are promising materials for photovoltaic applications, which have demonstrated a rapid rise in photovoltaic performance in a short period of time. We report a facile one-step method to fabricate planar heterojunction perovskite solar cells by chemical vapor deposition (CVD), with a solar power conversion efficiency of up to 11.1%. We performed a systematic optimization of CVD parameters such as temperature and growth time to obtain high quality films of CH3NH3PbI3 and CH3NH3PbI3-xClx perovskite. Scanning electron microscopy and time resolved photoluminescence data showed that the perovskite films have a large grain size of more than 1 micrometer, and carrier life-times of 10 ns and 120 ns for CH3NH3PbI3 and CH3NH3PbI3-xClx, respectively. This is the first demonstration of a highly efficient perovskite solar cell using one step CVD and there is likely room for significant improvement of device efficiency. [ABSTRACT FROM AUTHOR]

Titanium oxide (TiO 2) and tin oxide (SnO 2) are the most commonly used electron transport materials for high-efficiency n-i-p perovskite solar cells (PSCs); however, several limiting properties of TiO 2 and SnO 2 adversely affect device performance. This study describes a facile method to synthesize SnO 2 :TiO 2 hybrid nanocrystals (NCs) to construct electron transport layers (ETLs) with the advantageous properties of both SnO 2 and TiO 2 for n-i-p PSCs. The optimized SnO 2 :TiO 2 ETL exhibited better surface morphology, well-matched band alignment, higher direct current conductivity, and enhanced electron extraction and transport compared to pristine TiO 2 and SnO 2 ETLs. Moreover, perovskite films deposited on SnO 2 :TiO 2 ETLs exhibited a higher crystallinity and lower trap-state density than those on TiO 2 or SnO 2 ETLs. Therefore, SnO 2 :TiO 2 -based devices showed high performance (with a power conversion efficiency of 23.19%) and stability (with more than 83% retention of the initial efficiency after 800 h of continuous illumination). This study provides a new method for developing low-cost and efficient ETLs for n-i-p PSCs and confirms that constructing SnO 2 :TiO 2 hybrid ETL is an effective method to fabricate high-efficiency and stable planar perovskite solar cells. [Display omitted] • A facile method was developed to synthesize SnO 2 :TiO 2 hybrid nanocrystals. • The SnO 2 :TiO 2 hybrid ETL exhibited the advantageous properties of both TiO 2 and SnO 2. • Perovskite films deposited on SnO 2 :TiO 2 ETLs exhibited a high crystallinity and low trap-state density. • SnO 2 :TiO 2 -based devices had a PCE of 23.19% with >83% retention after 800 h of continuous illumination. [ABSTRACT FROM AUTHOR]

The device performance of CdS/CdTe solar cells largely depends on not only the back ohmic contact, but also the conformality of CdS window layer coating. In order to reduce the light absorption loss in CdS, the CdS thickness is usually less than 100 nm. However, pinholes in CdS and non-conformal coverage of CdS on transparent conducting oxide layer will cause shunting thus leading to device performance degradation and failure. In this paper, low-temperature and low-cost fabrication methods, i.e., chemical bath deposition and electrochemical deposition, were used to deposit CdS and CdTe, respectively. It was found that the yield of device was around 20 % due to shunting. In order to alleviate this problem, a compact layer of TiO was inserted between the fluorine-doped tin oxide and CdS as a buffer layer. The thickness effect of TiO was studied and showed that devices with thin (20 nm thickness) TiO performed better than the counterparts with thick layers. It was discovered that device yield improved to 80 % and stability in air substantially improved with TiO layer. [ABSTRACT FROM AUTHOR]

Unique light-matter interaction at nanophotonic regimecan be harnessedfor designing efficient photonic and optoelectronic devices such assolar cells, lasers, and photodetectors. In this work, periodic photonnanowells are fabricated with a low-cost and scalable approach, followedby systematic investigations of their photon capturing propertiescombining experiments and simulations. Intriguingly, it is found thata proper periodicity greatly facilitates photon capturing processin the nanowells, primarily owing to optical diffraction. Meanwhile,the nanoengineered morphology renders the nanostructures with a broad-bandefficient light absorption. The findings in this work can be utilizedto implement a new type of nanostructure-based solar cells. Also,the methodology applied in this work can be generalized to rationaldesign of other types of efficient photon-harvesting devices. [ABSTRACT FROM AUTHOR]