Crystalline silicon solar cells have evidenced a continuous increase in solar-to-electricity conversion efficiency and a rapid decrease in market price over the past years. The efficiency of c-Si solar cell is approaching its theoretical limit, leaving limited endeavor for further improvement. The cost of photovoltaic system is closely related with the efficiency of solar cells. Therefore, it is crucial to achieve a high efficiency while keeping the manufacturing cost of solar cells low. Multi-junction photovoltaics are proven to deliver higher performance than single-junction architectures, making them ideally suited for deployment in an increasingly efficiency-driven solar industry. Conventional multi-junction cells based on III-V semiconductors reach up to 46% efficiency, but are so costly to manufacture that they are only currently useful for space and solar concentrator photovoltaics. The hybrid multi-junction configurations, combining mature silicon PV technology with the emerging technologies, provide a vital path to achieving low-cost, high-efficiency photovoltaic cells. The hybrid approach enables to combine the distinctive advantages of each photovoltaic technology and avoids the necessity of expensive materials and complicated manufacturing. Recently, perovskite/c-Si monolithic tandem solar cells are attracting extensive attention due to the potential to surpass 30% efficiency in a low-cost manufacturing approach. For this purpose, planar perovskite solar cells made entirely via solution processing at low temperatures offer promise for simple manufacturing and compatibility with c-Si technology to construct tandem devices. However, the efficiency and stability of low-temperature planar perovskite cells are typically inferior to those of their high-temperature processed mesoscopic counterparts. We developed a contact passivation strategy using chlorine-capped TiO2 colloidal nanocrystal (NC) film as electron-selective contact that mitigates interfacial recombination and improves interface binding. This enabled us to fabricate planar solar cells with certified efficiencies of 19.5% for an active area over 1.0 cm2. Solar cells with passivated contact exhibit significantly improved MPP operation stability. The passivated contact technique also enables us to achieve efficient wide bandgap perovskite solar cells with an open-circuit voltage >1.25 V and fill factor >80%. Our contact passivation approach offers a promising path to developing highly efficient perovskite/c-Si or perovskite/perovskite tandem photovoltaic devices.


Seminar, May 26, 2017, 16:00. Seminar Room

Hosted by Prof. Gerasimos Konstantatos