Lead-Free Nanocrystal Inks for Flexible Optoelectronic Devices

The exploration of AgBiS 2 quantum dots (QDs) as an environmentally friendly alternative to previously-explored infrared-absorbing QDs has continued to gain interest in the past few years. Applications in optoelectronic devices are facilitated by colloidally stable inks that can be used to deposit films with favorable material properties on diverse substrates, including flexible substrates applicable to lightweight and wearable sensors. Here, we demonstrate that a rapid biphasic ligand exchange process can be used to make a AgBiS 2 QD ink. The properties of deposited films are explored in lateral photoconductive devices and in heterojunction photovoltaic devices. In addition to this, we also demonstrated the use of this environmentally benign QD ink in flexible devices: the photo response was unchanged when the device was flat or bent. These results demonstrate the versatility of solution-phase ligand exchange approaches to QD-based optoelectronic devices.