NREL - Page 2

Researchers from the University of North Carolina at Chapel Hill, Colorado School of Mines, National Renewable Energy Laboratory (NREL), University of Toledo and University of California San Diego have pointed out that the light-emitting diodes (LEDs) used in indoor testing of perovskite solar cells do not expose them to the levels of ultraviolet (UV) radiation that they would encounter in actual outdoor use. 

The scientists reported degradation mechanisms of p-i-n–structured perovskite solar cells under unfiltered sunlight and with LEDs. Weak chemical bonding between perovskites and polymer hole-transporting materials (HTMs) and transparent conducting oxides (TCOs) reportedly dominate the accelerated A-site cation migration, rather than direct degradation of HTMs.

Researchers at NREL, BlueDot Photonics, University of Washington, Colorado School of Mines and Rochester Institute of Technology have developed a vapor deposition technique based on continuous flash sublimation (CFS) to fabricate all-inorganic perovskite thin films in under 5 minutes in a continuous process. The adoption of the proposed approach may also result in higher power conversion efficiencies of perovskite solar cell.

Schematic illustration of the continuous flash sublimation (CFS) approach consisting of a mechano-chemical synthesis of the source powder (here CsPb(I_xBr_1−x)₃), the high-throughput deposition process in a home-made evaporation system, and a short post-annealing treatment to improve thin-film quality. Image from Journal of Materials Chemistry A

The team described the new technique as a non-batch process that solves two problems associated with the use of established vapor processing in perovskite material manufacturing – the slow speed of deposition and the non-continuous nature of batch processing.

In an effort to tackle the challenge of perovskite solar cells' thermal instability, researchers at City University of Hong Kong (CityU), National Renewable Energy Laboratory (NREL) and Huazhong University of Science and Technology have developed a unique type of self-assembled monolayer, or SAM for short, and anchored it on a nickel oxide nanoparticles surface as a charge extraction layer. This method dramatically enhanced the thermal robustness of perovskite solar cells, according to Professor Zhu Zonglong of the Department of Chemistry at CityU.

“By introducing a thermally robust charge extraction layer, our improved cells retain over 90% of their efficiency, boasting an impressive efficiency rate of 25.6%, even after operated under high temperatures, around (65℃) for over 1,000 hours. This is a milestone achievement,” said Professor Zhu.

Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and the University of Toledo have found that perovskite solar cells should be subjected to a combination of stress tests simultaneously to best predict how they will function outdoors.

The team used a state-of-the-art p-i-n PSC stack (with PCE up to ~25.5%) to show that indoor accelerated stability tests can predict 6-month outdoor aging tests. Device degradation rates under illumination and at elevated temperatures are most instructive for understanding outdoor device reliability. The team also found that the indium tin oxide (ITO)/self-assembled monolayer (SAM)-based hole transport layer (HTL)/perovskite interface most strongly affects the device operation stability. Improving the ion-blocking properties of the SAM HTL increases averaged device operational stability at 50°C–85°C by a factor of ~2.8, reaching over 1000 h at 85°C and to near 8200 h at 50°C with a projected 20% degradation, which is among the best to date for high-efficiency p-i-n PSCs.

Verde Technologies, a perovskite-focused thin-film solar company, has announced a new exclusive partnership with the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and Northern Illinois University (NIU) to work collaboratively on the commercialization of perovskite solar cells. 

By combining NREL's and NIU’s expertise with Verde's cutting-edge manufacturing techniques, this collaboration aims to unlock the potential of efficient, safe, low-cost perovskite solar panels at an unprecedented scale.

Researchers from Rice University, National Renewable Energy Laboratory (NREL), Lawrence Berkeley National Laboratory, CNRS and HZB have designed a conductive adhesive-barrier (CAB) that translates >99% of photoelectric power to chemical reactions. The device combines halide perovskites with electrocatalysts and could serve as a platform for a wide range of chemical reactions that use solar-harvested electricity to convert feedstocks into fuels.

The CAB enables halide perovskite-based photoelectrochemical cells with two different architectures that exhibit record solar-to-hydrogen (STH) efficiencies. 

Researchers from the University of Toledo, NREL and the University of Colorado Boulder have designed highly efficient, bifacial, single-junction perovskite solar cells based on a p-i-n (or inverted) architecture. In this work, the team showed that bifacial perovskite photovoltaics technology has the potential to outperform its monofacial counterparts.

The team used optical and electrical modeling to guide the optimization of the transparent conducting rear electrode and perovskite absorber layer using a p-i-n device architecture, achieving a high bifaciality of about 91%–93% and a high front-side illumination PCE of over 23%. Under concurrent bifacial measurement conditions, the equivalent, stabilized bifacial power output densities were 26.9, 28.5, and 30.1 mW/cm² under albedos of 0.2, 0.3, and 0.5, respectively. 

Researchers from Northern Illinois University, National Renewable Energy Laboratory (NREL), Northwestern University and Argonne National Laboratory have reported a bilayer back electrode configuration consisting of an Ni-doped natural graphite layer with a fusible Bi-In alloy. This back electrode can be deposited in a vacuum-free approach and enables perovskite solar cells (PSCs) with a power conversion efficiency of 21.0%. These inexpensive materials and facile ambient fabrication techniques can help provide an appealing solution to low-cost PSC industrialization.

A thin layer of gold or silver can help improve the efficiency of perovskite solar cells, but the researchers have found a less expensive material that will enable commercialization of the technology without exorbitant cost.  “A layer of gold in a solar panel or even a layer of silver is probably too expensive,” said Kai Zhu, a senior scientist in the Chemistry and Nanoscience Center at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL). “It would make the solar panel not affordable for most people.”

Researchers from the University of Toronto in Canada, Northwestern University, The University of Toledo and University of North Carolina at Chapel Hill in the United States, King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, Yunnan University in China, Ecole Polytechnique Fedérale de Lausanne (EPFL) in Switzerland and University of Warwick in the UK have developed a triple-junction perovskite solar cell with a record efficiency of 24.3% with an open-circuity voltage of 3.21 V. 

The NREL has certified the cell’s quasi-steady-state efficiency as 23.3%, which the team stated is the first reported certified efficiency for perovskite-based triple-junction solar cells. They added that triple-junction perovskite solar cells have so far demonstrated a maximum efficiency of around 20%.

Researchers at the National Renewable Energy Laboratory (NREL), City University of Hong Kong, École Polytechnique Fédérale de Lausanne (EPFL), University of Kentucky, University of Colorado, University of Toledo and Brown University have developed a concept  that simplifies the process of manufacturing perovskite solar cells, which could accelerate their path toward commercialization.

Perovskite solar cells are made by sequentially depositing various layers onto a conductive glass substrate, requiring multiple coatings to create the necessary full device structure. The new technique eliminates or combines some of those steps, thereby simplifying the manufacturing process, which could lead to lower manufacturing costs.