Indoor solar

Researchers from Taiwan's National Yang Ming Chiao Tung University and Flexwave have developed a self-adaptive interfacial nanostructure (SAIN) for the hole-extraction contacts of inverted perovskite solar cells, reporting a power conversion efficiency (PCE) approaching 20% under standard 1-sun illumination and 38.16% under indoor lighting at 2,000 lux - a figure that climbs above 40% once paired with an optical enhancement film, placing the device among the most efficient indoor perovskite solar cells reported to date.

The team explains that "regular" n-i-p configurations tend to reach higher efficiencies, but inverted PeSCs offer better long-term stability and are easier to stack into multijunction devices, making the p-i-n architecture an attractive target for further improvement. A major bottleneck in inverted PeSCs is the buried hole-transport layer (HTL) sitting beneath the perovskite film. Because the perovskite crystallizes directly on top of it, the HTL's quality shapes both the interface and the growing perovskite layer itself, and a poor HTL drives up non-radiative recombination - carriers lost to defects rather than converted into current, which shows up as low photoluminescence quantum yield in the finished film. Today's leading inverted devices typically grow their perovskite on either a hole-conducting polymer such as poly(triarylamine) (PTAA) or a self-assembled monolayer (SAM) built from carbazole-based molecules. Each has drawbacks: high-quality PTAA is costly to produce, while SAMs are difficult to deposit as a conformal, densely packed layer, which hurts device-to-device reproducibility. Both materials are also hydrophobic, complicating full-coverage perovskite deposition over large areas. Hybrid PTAA-plus-SAM contacts have been explored to combine their strengths, but so far only for standard 1-sun operation, leaving their potential for indoor photovoltaics untested.

Researchers from India's Indian Institute of Technology (IIT) Mandi have developed semi-transparent perovskite solar cells (ST-PSCs) based on compositionally tuned MAPbI₂.₆Br₀.₄ films, demonstrating a well-balanced trade-off between transparency and efficiency for building-integrated photovoltaics (BIPVs) and indoor energy harvesting.

The team engineered the perovskite absorber by systematically substituting methylammonium bromide (MABr) with methylammonium iodide (MAI) in MAPbI₃ precursors, while simultaneously varying precursor concentrations from 1 M down to 0.15 M. This dual strategy enabled precise control over both halide composition and film thickness - two key parameters governing optical transmission and photovoltaic performance.

On July 11, China's Xianyang City held a signing ceremony for six optoelectronic industry projects in its High-tech Zone, totaling an investment of 7.8 billion yuan (approximately US$1.1 billion). Among the projects is a notable perovskite initiative led by Xi’an Tianjiao New Energy, focused on lightweight and flexible perovskite solar technologies.

The project builds on technology developed by Professor Wu Chaoxin’s team at Xi’an Jiaotong University, including a low-cost large-area fabrication process and high-reliability thin-film encapsulation. These advances are said to significantly improve both power conversion efficiency and operational stability, enabling ultra-thin, lightweight, and bendable photovoltaic devices.

Perovskia Solar has announced that it has been awarded a €2.25 million grant from the European Innovation Council (EIC) Accelerator, alongside a potential equity investment from the EIC Fund. The Swiss company, which develops and manufactures custom perovskite solar cells for indoor applications, says this dual support will help accelerate its scale-up and strengthen its position in the indoor photovoltaics market.

In addition to the non-dilutive grant, the EIC Fund has indicated its intention to co-invest in Perovskia’s upcoming financing round, with the potential to match up to 50% of the round subject to due diligence. The EIC Accelerator is considered one of Europe’s most competitive funding programs for deep-tech innovation, with a selection rate of around 5-7%.

Halocell Energy recently secured a financial boost from the Australian federal government to scale up production of its indoor perovskite PV modules.

The company has been awarded AUD 606,680 under the Australian Government’s Industry Growth Program to expand its perovskite PV manufacturing capabilities and upgrade its production facility in Wagga Wagga, New South Wales. The new funding will support an increase in annual output of Halocell’s indoor perovskite PV modules from around 7,000 units today to approximately 100,000 units per year.

Zhenyao Technology, a China-based global provider of e-paper application solutions, recently launched a 31.5-inch full-color e-paper display advertising screen equipped with perovskite photovoltaic cells by Yanhe Solar. 

The product reportedly achieves completely passive operation for the first time in commercial-grade e-paper display devices, requiring no external power supply or replacement of the built-in battery, and can operate continuously using only ambient light. 

Researchers at the University of Queensland and Southwest University have developed a vapor-based fabrication strategy for lead-free tin-based halide perovskite (THP) indoor solar cells, addressing challenges in crystallization control while achieving high efficiency under low-light conditions.

A central challenge in thermally evaporated THP films is their complex and poorly controlled crystallization kinetics, which often leads to defects and performance losses. To overcome this, the team introduced formamidine acetate (FAAc) as a vapor-deposited additive during the formation of FASnI₂Br films. FAAc coordinates with SnI₂ to form a metastable SnI₂-FAAc intermediate phase. This intermediate slows and regulates the solid-state reaction pathway, allowing more controlled crystal growth. At the same time, FAAc reduces the surface free energy of the underlying SnI₂ layer, enabling more uniform deposition of the subsequent FABr layer. This dual effect - kinetic regulation and improved film wetting - results in higher-quality perovskite films with fewer defects and significantly suppressed trap-assisted recombination.

Researchers from Nanyang Technological University (NTU) have demonstrated fully vacuum‑processed ultrathin perovskite solar cells with MAPbI₃ absorber layers down to around 10 nm, achieving multi‑percent efficiency together with high transparency for building‑integrated use.

The team thermally evaporated MAPbI₃ in a planar p–i–n architecture and varied the absorber thickness from about 10 nm to several hundred nanometers. Devices with 10 nm, 30 nm, and 60 nm layers reached power conversion efficiencies of roughly 7%, 11%, and 12%, respectively, with open‑circuit voltage and fill factor remaining comparable to conventional 300–900 nm “bulk” devices, indicating low trap density and good optoelectronic quality.

Researchers from the University of Ljubljana have reported one of the longest continuous indoor studies of perovskite solar cells (PSCs) to date, tracking their performance and environmental behavior across a 2.5-year real-world deployment. The team evaluated sixteen small-area devices based on a double-cation, double-halide perovskite composition, using self-powered Bluetooth Low Energy (BLE) monitoring nodes placed in occupied indoor environments. This work provides new insight into long-term stability challenges under realistic lighting conditions - an area of growing importance as perovskite photovoltaics move toward integrated, low-power IoT applications.

Over the study period, the PSCs were monitored in multiple indoor locations under varying illumination spectra, temperatures, and relative humidity. The results revealed lifetimes ranging from 70 to 522 days, underscoring the large variability in perovskite stability under actual use conditions. Importantly, device degradation showed a measurable correlation with ambient humidity, suggesting that moisture management remains a key reliability bottleneck, even in controlled indoor environments.

BiLight Innovations has launched three flagship innovations at CES: a flexible and lightweight rollable photovoltaic (PV) curtain, a lithium-free perovskite electronic nameplate and a portable solar scroll.

Targeting core home and office scenarios, these products aim to redefine the boundaries of traditional photovoltaic applications. Through technological breakthroughs in flexibility, battery-free design, and scenario-based integration, the launch has attracted widespread attention across the show floor.