ph0c00491_si_001.pdf (255.71 kB)
Solution-Processed p‑Type Copper Thiocyanate (CuSCN) Enhanced Sensitivity of PbS-Quantum-Dots-Based Photodiode
journal contribution
posted on 2020-07-02, 14:15 authored by Ibrahima Ka, Luis F. Gerlein, Ivy M. Asuo, Soraya Bouzidi, Dawit M. Gedamu, Alain Pignolet, Federico Rosei, Riad Nechache, Sylvain G. CloutierLead
sulfide (PbS) quantum dots (QDs) exhibit outstanding size-dependent
properties that can be harnessed for optoelectronic applications.
For example, they can be used for broadband light detection thanks
to their band gap, which can be tuned from the UV to near-infrared.
Recent reports show that reducing the dark current in PbS-QDs-based
photodetectors leads to improved performance. To this end, we explore
the use of low-cost solution-processed p-type copper thiocyanate (CuSCN)
films as hole-transporting layer in PbS-QD-based photodetectors. We
demonstrate that depositing the CuSCN layer prior to the evaporation
of the metal electrode (silver or gold) significantly reduces the
dark current, regardless of the electrode material. In turn, the on–off
ratio and the detectivity of the fabricated photodiodes have also
been improved from 6 to 200 and 109 to 1011 cm
Hz1/2 W–1, respectively. Moreover, the
response time of the photodiodes is preserved when using the CuSCN
layer. The thin CuSCN film incorporated between the PbS QD layer and
the metal electrode can be engineered to enhance the performance of
broadband photodetectors, in a way that is compatible with standard
processing approaches.