Physics of organic solar cells
Organic solar cells (OPV) based on non-fullerene molecular acceptors can now achieve high photovoltaic performance (~17-18% efficiency), but it remains unclear how electron-hole pairs can overcome their mutual Coulomb attraction and separate efficiently. To this end we use femtosecond optical techniques to precisely track and reveal the charge generation mechanism in these promising materials.
Organic and perovskite are promising materials for next-generation solar cells with niche applications such as building-integrated and flexible PV, but further improvement in terms of both efficiency and stability are needed for commercialisation. Through studying the basic material and electronic properties of these materials, we develop processing and fabrication strategies to improve their device performance, pathing the way towards product commercialisation.
Exciton and spin physics in organic semiconductors
One fundamental difference between organic and inorganic semiconductors is the energy difference between the lowest spin-singlet (S=0) and triplet exciton states (S=1). For crystalline inorganic materials these spin states are degenerate, whereas for organic materials the lowest-lying triplet exciton state are typically much lower in energy than the singlet state due to strong electron-electron interactions. Managing the dynamics of dark spin-triplet electronic states is thus crucial for achieving high-performance optoelectronic devices based on organic semiconductors.
Design of next-generation photodetectors
Photodetectors are an essential component in a wide range of technologies, ranging from image sensors, health monitoring, optical communications, photovoltaics and manufacturing process monitoring. With the emergence of internet of things (IoT), there is an increasing demand for smart and unobtrusive photodetectors that are flexible, biocompatible and self-powered. We explore the use of organic electronic materials to meet this demand.