Single-junction solar cells are approaching their theoretical efficiency limit (33.7 %), therefore further development of photovoltaic technologies is inseparable from the creation of solar cells with two or more junctions. Dual-junction (tandem) solar cells enable more efficient utilization of the solar spectrum by combining a wide-bandgap top cell with a narrow-bandgap bottom cell, most commonly silicon. Such an architecture already allows the theoretical limit of single-junction cells to be exceeded, achieving efficiencies of more than 35 %.
At present, the highest efficiencies are demonstrated by III–V semiconductor/silicon tandem cells; however, their practical application is limited by high cost, complex fabrication, and the use of rare chemical elements. For these reasons, they are mainly employed in the space industry. In contrast, perovskite/silicon tandem solar cells represent a promising alternative due to simpler and lower-cost manufacturing technologies, but their further development is hindered by stability issues and significant open-circuit voltage losses of wide band gap perovskite solar cells (PSCs). These losses are caused by energy level mismatch between the perovskite and charge-transport layers, as well as by intensive recombination at perovskite surfaces due to defects formed during crystallization.
The aforementioned problem can be addressed by developing dual-purpose organic compounds that are capable not only of efficiently transporting charge carriers but also of reducing the density of perovskite surface defects, thereby improving efficiency and stability. The simplest approach to achieving this goal is the modification of well-known aromatic hole-transporting self-assembling monolayers by introducing additional functional groups into their structure (e.g., quaternary ammonium groups) that can interact with perovskite surface defects.
Period of project implementation: 2026-07-01 - 2026-08-31
Project coordinator: Kaunas University of Technology
