Thin Film Perovskite Solar Panels: How Efficient Are They?
There’s a new (or almost new) record in the field of single-junction perovskite photovoltaics. A group of scientists in China has pushed the efficiency of converting light into electricity even higher, continuing a series of successes in this field. In fact, the thin-film perovskite solar cells developed by Professor Xu Jixian and his team at the University of Science and Technology China (USTC) already hold two previous world records. The same group achieved these results in 2022 and 2023, and today the bar has been raised to 26.7%.
A Noteworthy Exception
This figure is reported in the latest update of the Solar Cell Efficiency Tables, a scientific publication tracking the global progress of solar cells and modules for nearly 30 years. The most important criterion for inclusion in the tables is that the results must be independently verified by a recognized testing center.
USTC’s thin-film perovskite solar panel was included in Table 2, which the authors call “noteworthy exceptions” for single-junction cells and submodules. What does this mean? Although the products listed show record-breaking performance, for one reason or another, they do not qualify for the official Guinness World Records.
The issue with the new Chinese solar panel is size. The team achieved 26.7% efficiency on a very small area, just 0.05 square centimeters. This is too small for the lead halide perovskite solar cell to be classified as an absolute record. To qualify for official classification (Table 1 of the publication), the unit must have a surface area of 1 square centimeter or more.
A New Process for Thin-Film Perovskite Solar Panels
But even so, it is an outstanding result. “This marks the third consecutive year that Professor Xu’s team has set a new world record for efficiency […] following the achievements of 2022 and 2023,” stated the university in a press release. “In 2023, the team achieved an innovative certified efficiency of 26.1% for its inverted perovskite solar cell, surpassing the 26% efficiency mark and breaking the dominance of conventional solar cells.”
The continuous success is grounded in refined manufacturing techniques.
Perovskite solar cells are third-generation cells that use hybrid organic-inorganic materials as the light-absorbing layer. It has been shown that the crystallographic orientation of the perovskite is one of the key factors determining the efficiency of photovoltaic devices. According to the literature, different crystalline faces of these compounds have distinct chemical, physical, and optoelectronic properties.
Another key factor influencing the performance of these n-i-p structure units is the buried interface between the perovskite layer and tin oxide. Defects at this level can lead to non-radiative recombination losses, thus reducing photoelectric conversion efficiency. In previous research, strategies to simultaneously achieve the preferred crystallographic orientation and a good buried interface mainly relied on introducing additional passivation layers, which increased the fabrication complexity.
Professor Xu’s team tackled this challenge by developing a simple yet effective preparation method. The process involves adding a special bifunctional ligand to the perovskite precursor solution. This compound not only enhances the orientation of the growing crystals but also helps eliminate defects from the interface.