January 2025

Researchers from China's Wuhan University and Hubei University have examined the long-term stability problem of tin-lead perovskites under irradiation, counterintuitively discovering an irreversible phase reconstruction process. 

The evolution from tin-lead perovskites to a reconstruction of lead perovskites under light. Image from: Nature Communications

Tin-lead perovskite materials show promise for all-perovskite tandem solar cells, offering an optimal bandgap that significantly boosts power conversion efficiency. However, light-induced degradation, particularly in ambient air, remains a major obstacle to their long-term stability. Unlike single-metal perovskite materials, tin-lead perovskite degrades through distinct mechanisms, making it crucial to understand how it deteriorates under light and air exposure.

Researchers from the University of Twente, Academy of Sciences of the Czech Republic, AMOLF, Universidad Andres Bello and University of Oxford have developed a way to create highly ordered semiconductor material at room temperature, that could make optoelectronics more efficient by controlling the crystal structure and reducing the number of defects at the nanoscale.

The team focused on metal halide perovskites. Making these materials with one single orientation (or in other words with highly ordered grains) has been a challenge and thus far, they have mainly been used in the non-ordered polycrystalline form. This can limit their use in applications such as LEDs, where high order and low density of defects are needed. Normally, these highly ordered semiconductors require high processing temperatures. But in this new process, the researchers skip the heat and build up the material layer by layer using a pulsed laser.

Researchers from China's Hebei University of Technology, Fudan University, Fuyang Normal University, Chinese Academy of Sciences (CAS), Macau University of Science and Technology, Kunming University of Science and Technology and France's CNRS have reported an innovative passivation strategy that is said to enable record power conversion rates and enhanced operational longevity of single junction and tandem perovskite solar cells (PSCs).

The team has developed this innovative strategy to address the issue of interfacial trap-assisted nonradiative recombination, which has been known to hinder the performance of perovskite-based photovoltaic technologies. The new passivator is identified as L-valine benzyl ester p-toluenesulfonate (VBETS) and using it under optimal conditions yielded PSCs that achieved a power conversion efficiency (PCE) of 26.28%. 

Technology research and market intelligence company IDTechEx has explored the perovskite PV market, forecasting that annual perovskite PV revenue will reach almost US$12 billion by 2035.

IDTechEx also sees perovskite/silicon tandem solar panels as "the most significant opportunity for this sector" and "are overall anticipated to dominate the perovskite PV market". Their similar mechanical properties to single-junction silicon solar, whilst achieving higher PCEs, makes them particularly suited for traditional solar applications, including solar farms and rooftop application. 

Hybrid perovskites show piezoelectric properties due to polarization and centro-symmetry breaking of PbX₆ pyramids (X = I^-, Br^-, Cl^-). Researchers from The Hebrew University of Jerusalem, Polish Academy of Sciences and Nanyang Technological University recently examined the piezoelectric response of quasi-2D perovskites using various barrier molecules: benzyl amine (BzA), phenylethyl amine (PEA), and butyl diamine (BuDA).

Utilizing piezoelectric force microscopy measurements, the team determined the piezoelectric coefficient (d33) where BuDA exhibits a substantial response with values of 147 pm V^–1 for n = 5, better than the other quasi-2D and 3D perovskite counterparts. Density functional theory calculations revealed distorted bond angles in the PbBr₆ pyramids for quasi-2D perovskites, enhancing symmetry breaking. 

Researchers from China's Xi’an Jiaotong University, Huazhong University of Science and Technology, Fudan University, ULVAC-PHI Instruments, National University of Singapore (NUS), Sweden's Uppsala University and EPFL have developed a self-assembled bilayer (SAB) that can be used as a hole contact material that grants improved adhesive contact with the perovskite film. 

A schematic illustration of the inverted PSCs. Image from: Nature Energy

The team went on to fabricate an inverted perovskite solar cell that utilizes the self-assembled bilayer (SAB) as a hole-selective molecular contact. The cell was made with a substrate made of glass and transparent conductive oxides (TCOs), the proposed bilayer, the perovskite absorber, an ETL based on buckminsterfullerene (C60), a bathocuproine (BCP) buffer layer, and a silver (Ag) metal contact. 

Researchers from EPFL and CSEM recently fabricated efficient (>20 %) and stable (T80 ∼ 720 h) planar FAPbI₃-based perovskite (1.54 eV) solar cells via a hybrid evaporation-spin coating process. 

FAPbI₃-based perovskite films were fabricated via a hybrid two-step evaporation-spin coating method in an inverted (p-i-n) configuration, and the effects of optimized parameters on the film growth and devices’ performances were investigated. Transferring these films into tandem devices atop single-side textured silicon heterojunction bottom cells, the team obtained an efficiency of >24 % under AM1.5 G illumination for monofacial devices with an active area of 1.21 cm². Furthermore, the bifacial devices generated >27 mW cm⁻² power output with 15 % rear illumination fraction.

Mellow Energy has announced the launch of what it refers to as "the world’s largest integrated flexible perovskite photovoltaic (PV) module" from its 100MW-scale production line. The module measures 1.2×1.6 square meters and weighs approximately 2.04 kilograms.

According to Mellow Energy, tests conducted by TÜV Rheinland, an internationally renowned testing and certification body, have confirmed that the 1.2×1.6-square-meter double-glass module achieves a full-area efficiency of 17.9% under standard testing conditions.

Monolithic all-perovskite tandem solar cells present a promising approach for exceeding the efficiency limit of single-junction solar cells. However, the substantial open-circuit voltage loss in the wide-bandgap perovskite subcell hinders further improvements in power-conversion efficiency. Now, researchers from China's Nanjing University, Renshine Solar (Suzhou) and Ecole Polytechnique Fédérale de Lausanne (EPFL) have developed wide-bandgap perovskite films with improved crystal orientation that suppress non-radiative recombination. 

The team showed that using two-dimensional perovskite as an intermediate phase on the film surface promotes heterogeneous nucleation along the three-dimensional perovskite facets during crystallization. Preferred orientations can be realized by augmenting the quantity of two-dimensional phases through surface composition engineering, without the need for excessive two-dimensional ligands that otherwise impede carrier transport. 

Increasing module efficiency and expanding manufacturing capacity play complementary roles in reducing costs of metal halide perovskite/silicon tandem solar modules, according to researchers at the U.S. Department of Energy's National Renewable Energy Laboratory (NREL). Each cost lever can play a similar role depending on a manufacturer’s ability to scale up and improve module performance.

They explain that tandem PV technology, created by pairing silicon with metal halide perovskites (MHPs) for example, can help create a solar module that can convert more sunlight to electricity than using silicon alone. This tandem technology is still in the early stages, and there are multiple options being pursued to integrate MHPs and silicon, with a lot of unknowns in terms of cost and performance. To address this gap, the researchers built a manufacturing cost model that combines laboratory processes with existing equipment and supply chains to compare different possible approaches at scale.