Solar Energy
Shedding light on perovskite films

Photovoltaics decisively contributes to sustainable energy supply. The efficiency of solar cells in directly converting light energy into electrical energy depends on the material used. Metal-halide perovskites are considered very promising materials for solar cells of the next generation. With these semiconductors named after their special crystal structure, a considerable increase in efficiency was achieved in the past years.
Meanwhile, perovskite solar cells have reached an efficiency of up to 25.5 percent, which is quite close to that of silicon solar cells that are presently dominating the market. Moreover, the materials needed for perovskite solar cells are rather abundant.
The solar cells can be produced easily and at low cost and they can be used for various applications. The theoretically achievable efficiency of perovskite solar cells is about 30.5 percent.
To approach this value, optoelectronic quality of perovskite semiconductors must be further increased. In principle, materials suited for photovoltaics are expected to not only absorb light, but to also emit it efficiently. This process is known as photoluminescence. The corresponding parameter, photoluminescence quantum efficiency, is perfectly suited to determine the quality of perovskite semiconductors.
Together with scientists from the Center for Advanced Materials (CAM) of Heidelberg University and the Technical University of Dresden, researchers of KIT’s Institute of Microstructure Technology (IMT) and Light Technology Institute (LTI) have now developed a model, by means of which photoluminescence quantum efficiency of perovskite films can be determined reliably and exactly for the first time. Their results are reported in Matter.
Materials Have More Optimization Potentials than Assumed
“With the help of our model, photoluminescence quantum efficiency under solar irradiation can be determined far more precisely,” says Dr. Paul Fassl from IMT. “Photon recycling is of high importance. This is the share of photons emitted by the perovskite, which is re-absorbed and re-emitted in the thin films.”
The researchers applied their model to methylammonium lead triiodide (CH3NH3PbI3), one of the perovskites of highest photoluminescence quantum efficiency. So far, it has been estimated to amount to about 90 percent.
Model calculations, however, revealed that it is about 78 percent. The scientists explain that previous estimations did not adequately consider the effect of light scattering and, hence, underestimated the probability of photons – the quantums of light energy – leaving the film before they are re-absorbed.
“Our results show that the potential for optimization of these materials is far higher than assumed,” says Dr. Ulrich W. Paetzold, Head of the Advanced Optics and Materials for Next Generation Photovoltaics Group of IMT. The team offers an open-source application based on the model, by means of which photoluminescence quantum efficiencies of various perovskite materials can be calculated.
Solar Energy
Battery boom drives Bangladesh lead poisoning epidemic

Battery boom drives Bangladesh lead poisoning epidemic
By Philippe ALFROY
Mirzapur, Bangladesh (AFP) April 1, 2025
Bangladeshi Junayed Akter is 12 years old but the toxic lead coursing through his veins has left him with the diminutive stature of someone several years younger.
Akter is one of 35 million children — around 60 percent of all children in the South Asian nation — who have dangerously high levels of lead exposure.
The causes are varied, but his mother blames his maladies on a since-shuttered factory that hastily scrapped and recycled old vehicle batteries for profit, in the process poisoning the air and the earth of his small village.
“It would start at night, and the whole area would be filled with smoke. You could smell this particular odour when you breathed,” Bithi Akter told AFP.
“The fruit no longer grew during the season. One day, we even found two dead cows at my aunt’s house.”
Medical tests showed Junayed’s blood had twice the level of lead deemed by the World Health Organization to cause serious, and likely irreversible, mental impairment in young children.
“From the second grade onward, he didn’t want to listen to us anymore, he didn’t want to go to school,” Bithi said, as her son sat next to her while gazing blankly out at the courtyard of their home.
“He cried all the time too.”
Lead poisoning is not a new phenomenon in Bangladesh, and the causes are manifold.
They include the heavy metal’s widespread and continued use in paint, in defiance of a government ban, and its use as an adulterant in turmeric spice powder to improve its colour and perceived quality.
A great many cases are blamed on informal battery recycling factories that have proliferated around the country in response to rising demand.
Children exposed to dangerous levels of lead risk decreased intelligence and cognitive performance, anaemia, stunted growth and lifelong neurological disorders.
The factory in the Akter family’s village closed after sustained complaints from the community.
But environmental watchdog Pure Earth believes there could be 265 such sites elsewhere in the country.
“They break down old batteries, remove the lead and melt it down to make new ones,” Pure Earth’s Mitali Das told AFP.
“They do all this in the open air,” she added. “The toxic fumes and acidic water produced during the operation pollute the air, soil and water.”
– ‘They’ve killed our village’ –
In Fulbaria, a village that sits a few hours’ drive north of the capital Dhaka, operations at another battery recycling factory owned by a Chinese company are in full swing.
On one side are verdant paddy fields. On the other, a pipe spews murky water into a brackish pool bordered by dead lands, caked with thick orange mud.
“As a child, I used to bring food to my father when he was in the fields. The landscape was magnificent, green, the water was clear,” engineer and local resident Rakib Hasan, 34, told AFP.
“You see what it looks like now. It’s dead, forever,” he added. “They’ve killed our village.”
Hasan complained about the factory’s pollution, prompting a judge to declare it illegal and order the power be shut off — a decision later reversed by the country’s supreme court.
“The factory bought off the local authorities,” Hasan said. “Our country is poor, many people are corrupt.”
Neither the company nor the Chinese embassy in Dhaka responded to AFP’s requests for comment on the factory’s operations.
Syeda Rizwana Hasan, who helms Bangladesh’s environment ministry, declined to comment on the case because it was still before the courts.
“We regularly conduct operations against the illegal production and recycling of electric batteries,” she said.
“But these efforts are often insufficient given the scale of the phenomenon.”
– ‘Unaware of the dangers’ –
Informal battery recycling is a booming business in Bangladesh.
It is driven largely by the mass electrification of rickshaws — a formerly pedal-powered means of conveyance popular in both big cities and rural towns.
More than four million rickshaws are found on Bangladeshi roads and authorities estimate the market for fitting them all with electric motors and batteries at around $870 million.
“It’s the downside of going all-electric,” said Maya Vandenant of the UN children’s agency, which is pushing a strategy to clean up the industry with tighter regulations and tax incentives.
“Most people are unaware of the dangers,” she said, adding that the public health impacts are forecast to be a 6.9 percent dent to the national economy.
Muhammad Anwar Sadat of Bangladesh’s health ministry warned that the country could not afford to ignore the scale of the problem.
“If we do nothing,” he told AFP, “the number of people affected will multiply three or fourfold in the next two years.”
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Solar Energy
Modi to kick off construction of India-Sri Lanka solar plant

Modi to kick off construction of India-Sri Lanka solar plant
by AFP Staff Writers
New Delhi (AFP) Mar 28, 2025
Indian Prime Minister Narendra Modi will launch the construction of a long-delayed solar power project during his upcoming visit to Sri Lanka, an official said on Friday.
Vikram Misri, the secretary of India’s foreign ministry, said Modi and Sri Lankan President Anura Kumara Dissanayake will witness a virtual groundbreaking ceremony for their joint-venture solar power project in the island’s northeast on April 5.
The proposed 120-megawatt venture in the northeastern coastal district of Trincomalee has stalled for years, but New Delhi backed it as a joint project between the neighbouring nations.
“This, in many senses, is going to be a milestone in the bilateral partnership,” Misri told reporters in New Delhi.
“They will together dedicate several projects that are being built with Indian assistance in Sri Lanka and will also witness the exchange of several MoUs pertaining to energy connectivity, digitisation, defence, health, and multisectoral grant assistance.”
The pair will watch the virtual groundbreaking from Sri Lankan capital Colombo. The costs of the project were not immediately available.
The groundbreaking, a day before Modi concludes his two-night visit to Sri Lanka, comes as Colombo grapples with the competing interests of its powerful northern neighbour and China, its largest lender.
Modi will be the first foreign head of government to visit the island nation under the new administration of leftist Dissanayake. He flies into Colombo on April 4 after attending a regional conference in Thailand.
Dissanayake’s first foreign visit after his election last year was to New Delhi in December.
Sri Lankan officials in Colombo said Modi and Dissanayake will travel to the northern Buddhist pilgrimage city of Anuradhapura on April 6.
Dissanayake travelled to Beijing in January, underscoring Sri Lanka’s delicate balancing act in maintaining ties with the two regional rivals.
New Delhi has been concerned about China’s growing influence in Sri Lanka, which it considers to be within its sphere of geopolitical influence.
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Solar Energy
A lifetime power source in miniature form

A lifetime power source in miniature form
by Riko Seibo
Tokyo, Japan (SPX) Mar 30, 2025
The batteries that power smartphones, electric vehicles, and drones often require frequent charging and degrade over time, leading to limited lifespan and environmental concerns. Now, a team at Daegu Gyeongbuk Institute of Science and Technology (DGIST) is exploring a nuclear alternative that could offer decades or even centuries of reliable power without recharging.
Su-Il In, a professor at DGIST, presented this breakthrough at the American Chemical Society’s Spring 2025 meeting, held March 23-27. His team is pioneering nuclear batteries that harness radiocarbon, a form of radioactive carbon known for emitting beta particles, to produce safe and long-lasting energy.
“The performance of Li-ion batteries is almost saturated,” explained In. This limitation, combined with the environmental toll of lithium extraction and disposal, has driven interest in more sustainable, high-endurance alternatives. Nuclear batteries, which convert radiation into electrical power, are emerging as a compelling solution.
Radiocarbon, or carbon-14, is a low-energy beta emitter that can be effectively shielded with a thin aluminum layer, making it a practical choice for safe nuclear batteries. Additionally, as a by-product of nuclear reactors, radiocarbon is affordable, widely accessible, and recyclable. Its extremely slow decay rate suggests that batteries powered by it could last thousands of years.
In a betavoltaic cell, beta particles from radioactive decay strike a semiconductor, generating electricity. In and his team developed a prototype using titanium dioxide as the semiconductor base, enhanced with a ruthenium-based dye. They further improved its performance through citric acid treatment, which reinforced the dye’s adhesion to the titanium dioxide.
This setup creates a cascade of electron transfer, known as an electron avalanche, triggered by the interaction of beta rays with the dye. The semiconductor efficiently captures the resulting charge and channels it through an external circuit to produce usable electricity.
Unlike earlier models with radiocarbon only on the cathode, the new design includes radiocarbon in both the cathode and the anode. This dual configuration boosts the number of beta particles generated and minimizes energy loss caused by the spatial separation of the components.
In testing, the improved prototype demonstrated a significant jump in energy conversion efficiency, increasing from 0.48% to 2.86%. This performance leap is attributed to the enhanced interaction between the radioactive material and the dye-sensitized semiconductor.
Such nuclear batteries could revolutionize numerous technologies, In noted. Medical implants like pacemakers could function for a lifetime without the need for replacement surgeries. Still, the current prototype converts only a small fraction of radioactive decay into electrical power, trailing behind the output of conventional lithium-ion systems.
To close this performance gap, future development will focus on refining the geometry of the beta source and improving the absorptive properties of the semiconductor material. These improvements could unlock higher power yields and broaden the range of applications.
As public attitudes toward nuclear technology evolve amid climate concerns, In emphasized the potential of small-scale, safe nuclear energy: “We can put safe nuclear energy into devices the size of a finger.”
Research Report:Next generation battery: Highly efficient and stable C14 dye-sensitized betavoltaic cell
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Daegu Gyeongbuk Institute of Science and Technology
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