The National Centre for Photovoltaic Research and Education (NCPRE) at IIT Bombay has marked a significant stride in perovskite solar cell (PSC) technology, achieving an efficiency exceeding 26%. This was accomplished through a novel method involving the fabrication of a semi-transparent PSC, which was then paired with a silicon-based solar cell.
Addressing the Stability Challenge in PSCs
While PSCs offer lower fabrication costs and high efficiency, they present a notable stability challenge. The IIT Bombay team tackled this by innovatively combining the PSC with a silicon solar cell in a tandem configuration, enabling the device to convert a larger portion of light into electricity. Prof. Dinesh Kabra from IITB highlights, “Perovskite solar cells, while recognized for their high-power conversion efficiency and lower production cost, have stability issues; our work has fabricated a stable 4T Si/perovskite tandem solar cell, exhibiting stability under various conditions.”
The 4T Tandem Device: A Solution to PSC Stability
The 4T tandem device not only allows for accurate performance measurements but also enhances the device’s efficiency and lifespan. The PSC, crafted from a thin film of perovskite, is transparent to near InfraRed light, making it applicable in various devices, including building and vehicle integrated photovoltaics. Prof. Kabra elucidates, “In our 4T tandem configuration, when the top low-cost perovskite solar cells fail, there is a possibility to replace the top cells with a new one since our tandem device is only optically coupled, potentially enhancing the lifetime of the overall devices.”
Academic Relevance and Future Implications
The tandem device demonstrated a high 26% power conversion efficiency and provided a comprehensive device architecture and fabrication process, contributing significantly to academic research. Prof. Kabra emphasizes the academic relevance, stating, “Our report not only shows the complete device architecture but also explains the fabrication process, as a typical practice of academic research.” The device also reduces the levelized cost of energy (LCOE) for tandem solar cells, providing a measure of the cost of electricity for different electricity generation methods.
The Road Ahead for Solar Power Generation
As nations globally embrace renewable energy sources, solar power generation is poised to become omnipresent, with perovskites playing a pivotal role. The study from IITB lays a foundational base for a wealth of knowledge yet to be explored and developed in the realm of perovskite solar cells and tandem devices based on them. The transparency of the PSC, which is useful in several devices, was measured for its power conversion efficiency (PCE), gauging the amount of light being converted into electricity. The tandem structure, while more resilient, allows for the top PSC layer to be easily replaced if it degenerates faster than the silicon cell.
The tandem configuration not only provides higher efficiency but also imparts greater stability to the device, thereby reducing its overall lifetime costs. The PSCs, despite their high efficiencies and low production costs, have been critiqued for their stability, especially in continuous heating conditions. The PSC was fabricated from a thin film of perovskite, which is transparent to near InfraRed light, making it versatile in various applications. The PSC recorded high efficiencies of 17.1% for a small area (0.175cm2) and 16% for a large area (0.805cm2). The researchers also demonstrated a very high 26% power conversion efficiency for the tandem device, marking one of the highest recorded efficiencies for such a device. The new tandem structure was far more resilient and stable under different environmental conditions, with a higher demonstrated efficiency. The researchers turned to tandem device architecture to address the stability issue of the PSC, layering it on top of a commercially available silicon solar cell.