October 2024

Researchers at the Korea Advanced Institute of Science and Technology (KAIST), Yonsei University, Gwangju Institute of Science and Technology (GIST) and Korea Institute of Ceramic Engineering and Technology (KICET) have reported a high-efficiency and high-stability organic-inorganic hybrid solar cell production technology that maximizes near-infrared light capture beyond the existing visible light range.

The research team suggested a hybrid next-generation device structure with organic photo-semiconductors that complements perovskite materials limited to visible light absorption and expands the absorption range to near-infrared. In addition, they focused on a common issue that mainly occurs in the structure and developed a solution to this problem by introducing a dipole layer - a thin material layer that controls the energy level within the device to facilitate charge transport and forms an interface potential difference to improve device performance.

Researchers from Helmholtz Zentrum Berlin (HZB) and École Polytechnique Fédérale de Lausanne (EPFL) have presented optimization strategies for top cell processing and integration into silicon heterojunction (SHJ) bottom cells based on industrial Czochralski (Cz)-Si wafers of 140 μm thickness. 

Schematic illustration of the perovskite/silicon tandem solar cell based on 140 μm Cz-Si. Image credit: ACS Applied Materials & Interfaces

The team showed that combining the self-assembled monolayer [4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid (Me-4PACz) with an additional phosphonic acid (PA) with different functional groups, can improve film formation when used as a hole transport layer improving wettability, minimizing shunt fraction and reducing nonradiative losses at the buried interface. 

Before reaching large-scale production and deployment of perovskite solar cells (PSCs), their entire lifecycle - from preparation and operation to discarding, needs to be carefully considered. In a recent study, researchers from Donghua University and Kyushu University used bio-derived chitin-based polymers to realize the full lifecycle regulation of air-processed PSCs by forming multiple coordinated and hydrogen bonds to stabilize the lead iodide and organic salt precursor inks, accelerating the solid–liquid reaction and crystallization of two-step deposition process, then achieving the high crystalline and oriented perovskites with less notorious charge defects in the open air. 

The air-prepared PSCs exhibited an efficiency of 25.18% with high preparation reproducibility and improved operational stability toward the harsh environment and mechanical stress stimuli. The modified PSCs displayed negligible fatigue behavior, keeping 92% of its initial efficiency after operating for 32 diurnal cycles (ISOS-LC-1 protocol). 

Perovskite solar cells (PSCs) that incorporate a 2D/3D perovskite layer tend to demonstrate enhanced stability compared to that of their purely 3D counterparts, possibly thanks to the superior chemical stability of the 2D perovskite layer. However, the poor electrical properties of the 2D perovskite layer also limit further improvement of device performance. Moreover, the most effective hole transport layer (HTL) in 2D/3D PSCs, lithium bis(trifluoromethylsulfonyl)imide (Li-TFSI)-doped 2,2′,7,7′-tetrakis(N,N-di(4-methoxyphenyl)amino)-9,9-spirobifluorene (spiro-OMeTAD), usually needs prolonged exposure to air to improve its conductivity, which to some extent increases the risk of water/oxygen infiltrating into the perovskite layer, leading to the degradation of the perovskite active layer.

Researchers at China's Henan University and Chinese Academy of Sciences (CAS) have developed a multifunctional dopant, tin oxysulfide (SnSO) in the spiro-OMeTAD layer, to improve the efficiency and stability simultaneously.

Researchers from Australia’s University of New South Wales (UNSW) Sydney have developed a defects passivation strategy for chloride-iodide-based perovskite. The team targeted the hard-to-avoid local defects in chloride-iodide-based perovskites, using two organic halide passivators named 4-chlorobenzylammonium chloride and 4-chlorobenzylammonium bromide. 

The scientists passivate both the surface and bulk of the perovskite thin film. The surface of the perovskite thin film is passivated with the bulky organic benzylammonium cations. The bulk of the perovskite thin film is passivated with the diffusion of chlorine or bromine. 

Semi-transparent solar cells are appealing for many different applications such as building-integrated photovoltaics (BIPVs), tandem solar cells and in wearable electronics. Perovskites could be ideal for semi-transparent applications as they are versatile and easy to optimize.

Semi-transparent perovskite solar cells (ST-PSCs) must try to maximize efficiency and transparency. Methods such as bandgap engineering, thinning perovskite layers, and creating discontinuous structures are being developed to improve their performance. However, challenges still remain with ST-PSC development, such as phase stability and defect management.

Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center (EFRC), University of Wisconsin-Madison, University of Colorado Boulder, Duke University and University of Utah have discovered a new process to induce chirality in halide perovskite semiconductors, which could open the door to cutting-edge electronic applications.

The development is the latest in a series of advancements made by the team involving the introduction and control of chirality. Chirality refers to a structure that cannot be superimposed on its mirror image, such as a hand, and allows greater control of electrons by directing their “spin.” Most traditional optoelectronic devices in use today exploit control of charge and light but not the spin of the electron.

Researchers from King Abdullah University of Science and Technology (KAUST) and  Helmholtz-Zentrum Berlin (HZB) have developed a perovskite-silicon tandem solar cell that achieves efficient charge extraction and interface passivation. The team improved the performance of blade-coated tandems by introducing 2D perovskite layers at the bottom interface. 

Image credit: Joule

These modifications enhanced the blade-coated tandem performance to a certified PCE of 31.2%, owing to efficient charge extraction and interface passivation. This work demonstrates the efficiency potential for scalable ink-based fabrication, emphasizing stability and manufacturability, which are crucial for the widespread adoption and commercial success of this promising photovoltaic (PV) technology.

Researchers from China's Dongguan University of Technology and Xi'an Jiaotong University have developed a spontaneous cooling strategy with a hot-pressing technique that enables the production of high-purity, wafer-scale, pinhole-free perovskite wafers with a reflective surface. 

This method can, according to the team, be extended to a variety of perovskite wafers, including organic-inorganic, 2D, and lead-free perovskites. The size of the wafer (with diameters of 10, 15, and 20 mm) can be tailored by changing the mold.

Tokyo Chemical Industry (TCI), a global supplier of laboratory chemicals and specialty materials, is now offering Phenylethylamine Hydroiodides materials, used for surface treatment of perovskite layers in solar panels. These materials improve the stability of the solar panels.

Research has shown that by applying the Phenylethylamine Hydroiodides materials, one can expect improved stability of over 90%. In one research, the 1,2-Benzenediethanamine Dihydroiodide was applied to a perovskite PV device (FTO/TiO2/SnO2/perovskite/Amine Iodide/Spiro-OMeTAD/Au), and achieved an increase in stability of over 90% after 1,100 hours. See here for more info.