Photovoltaic (PV) technologies, which convert light into electricity, are widely used around the world to generate renewable energy. Researchers in Hong Kong have developed a molecular treatment that significantly improves the efficiency and durability of perovskite solar cells.
A key part of the solution lies in the successful identification of critical parameters that determine the performance and lifetime of halogenated perovskites, a new generation of photovoltaic materials. This material has emerged as one of the most promising for PV devices due to its unique crystalline structure. The results of this research have been published in the journal Science.
Passivation et performance
Under the supervision of Assistant Professor LIN Yen-Hung of the Department of Electronic and Computer Engineering (HKUST) and the State Laboratory of Advanced Display and Optoelectronics Technologies, the research team explored various passivation methods. Passivation is a chemical process that reduces the number of defects or mitigates their impact in materials, thereby improving the performance and longevity of devices. The team focused on the molecular family of “amino-silanes» for the passivation of perovskite solar cells.
For the first time, the research team has demonstrated how different types of amines (primary, secondary and tertiary) and their combinations can improve the surfaces of perovskite films where many defects form. This improvement was achieved using methods “ex-situ» (outside the operating environment) and « in-situ » (in the operating environment) to observe the interactions of molecules with perovskites. In this way, molecules that significantly increase the photoluminescence quantum yield (PLQY) were identified, indicating fewer defects and better quality.
Development of tandem solar cells
Prof. Lin explained the importance of this approach for the development of tandem solar cells, which combine multiple layers of photoactive materials with different band gaps. This design maximizes the use of the solar spectrum by absorbing different parts of the sunlight in each layer, leading to higher overall efficiency.
In their demonstration, the team fabricated devices of medium (0.25 cm²) and large (1 cm²) sizes.
The experiment showed low photovoltage loss over a wide band gap range, while maintaining a high output voltage. These devices achieved high open-circuit voltages, exceeding 90% of the thermodynamic limit. Based on approximately 1,700 data sets from the existing literature, their results were among the best in terms of energy conversion efficiency.
Compatibility with industrial production
Prof. Lin pointed out that their treatment process not only improves the efficiency and durability of perovskite solar cells, but also is compatible with large-scale industrial production.
«This treatment is similar to the HMDS (hexamethyldisilazane) priming process widely used in the semiconductor industry.” he said.This similarity suggests that our new method can be easily integrated into existing manufacturing processes, making it commercially viable and ready for large-scale application..»
Article : « Bandgap-universal passivation enables stable perovskite solar cells with low photovoltage loss » – DOI: 10.1126/science.ado2302
