Solution processed perovskite is a new-generation thin film technology with solution inks for photovoltaics (PV) and light emitting diode (LED), suitable for application using printing and coating techniques. The world record efficiency of PV lies between silicon solar cell (first generation PV, 26.7%) and thin film solar cell (second generation, ~22%). The luminescent properties, i.e. colour tunability and external quantum efficiency (EQE), of perovskite-based LED are comparable to those of OLED.
We developed a series of ligand-perovskite inks and the PV efficiency was found to be above 20%. Recently, we also applied the inks for LED, with EQE close to 10%. The inks can be coated on substrates regardless of whether they are rigid or flexible with high throughput, and can greatly reduce the efficiency-cost-scalability gap. This ligand-perovskite ink technology is promising to be cost-efficiently utilised in the future PV/LED market and would be of great interest to PV/OLED companies as prospective strategies for future development.
The central technology is the ligand-perovskite ink, which is based on nanoscience and coordination chemistry. The ligand stabilises the perovskite precursor through coordination and enhances the thin film quality during deposition by controlling the intermediate. The use of the ink depends on the fabricated device and the in-detail parameters can be customised, for instance, 500 nm thick film for high performance PV solar panels and 50-100 nm for LED devices.
Advantages include the low-cost raw material, printable technology, light weight, high energy conversion efficiency and switchable PV-LED functions. It can bring potentially great economic value with a reduced efficiency-stability-scalability-cost gap of PV/LED devices.
The ink-based thin film technology is useful for new-generation PV/LED devices, such as flexible/portable devices, switchable PV/LED windows, smart buildings etc. Since perovskite PV technology is widely investigated by academic communities all over the world, the well-developed inks are also useful for the education/research sector with reduced entry level for junior researchers.