Energy level tuned indium arsenide colloidal quantum dot films for efficient photovoltaics
We introduce indium arsenide colloidal quantum dot films for photovoltaic devices, fabricated by two step surface modification. Native ligands and unwanted oxides on the surface are peeled off followed by passivating with incoming atomic or short ligands. The near infrared absorbing n type indium arsenide colloidal quantum dot films can be tuned in energy level positions up to 0.4 eV depending on the surface chemistry, and consequently, they boost collection efficiency when used in various emerging solar cells. As an example, we demonstrate p n junction between n type indium arsenide and p type lead sulfide colloidal quantum dot layers, which leads to a favorable electronic band alignment and charge extraction from both colloidal quantum dot layers. A certified power conversion efficiency of 7.92% is achieved without additionally supporting carrier transport layers. This study provides richer materials to explore for high efficiency emerging photovoltaics and will broaden research interest for various optoelectronic applications using the n type covalent nanocrystal arrays.Existing n type colloidal quantum dot materials easily lose their doping polarity in air. Here Song et al. passivate the reactive covalent surface of indium arsenide quantum dots to gain the energy level tunability and show p n junction type solar cells with 7.92% certified efficiency.
Nature Communications