Stable ultra-fast broad-bandwidth photodetectors based on α-CsPbI 3 perovskite and NaYF 4 :Yb,Er quantum dots

Photodetectors (PDs), especially those that respond in the infrared region, are highly desirable and have a wide range of applications ranging from cell phones, cameras, and home electronics to airplanes and satellites. Herein, we designed and fabricated PDs based on air-stable α-CsPbI3 QDs and an up-conversion material (NaYF4:Yb,Er QDs) using a facial low temperature spin-coating method. When the α-CsPbI3 QDs are surface-modified using NaYF4:Yb,Er QDs, their optical response is extended to the NIR region to allow broadband application from the UV to visible to NIR region (260 nm–1100 nm). The optoelectronic properties and compositional stability of the devices were also studied in detail. From the results, the PDs are capable of broad-bandwidth photodetection from the deep UV to NIR region (260 nm–1100 nm) with good photoresponsivity (R, 1.5 A W−1), high on/off ratio (up to 104) and very short rise/decay time (less than 5 ms/5 ms). It was found that the photoresponsivity performance of the PDs in this work is better than that of all the other previously reported perovskite QD-based PDs with a lateral device structure. Furthermore, the device performance shows very little degradation over the course of 60 days of storage under ambient conditions. The combination of remarkable stability, high performance broad-bandwidth photodetection, and easy fabrication suggest that these QDs are a very promising semiconducting candidate for optoelectronic applications.