Performance enhancement of perovskite/porous-Si photodetectors by reducing the dark current with concomitant use of graphene quantum dots in the active layer and bathocuproine on the back surface

Remarkable Enhancement of Detectivity and Stability in Flexible n–i–p-Type Perovskite Photodetectors by Concurrent Use of Various Two-Dimensional Materials: Doped Graphene, Graphene Quantum Dots, WS2, and h-BN

“…The lifetime for maintaining 50% of the initial R in the accelerated tests is estimated to be 16 h for the PD without GQDs, but becomes doubled for the PD with GQDs (32 h). These results suggest that the enhanced stabilities of the TETA-GR/WS 2 /h-BN/MAPbI 3 :GQDs/PTAA/Au PDs are believed to result from the high chemical stability and flexibility of the constituent 2D materialsTETA-GR, WS 2 , h-BN, and GQDsas previously reported. ,,, …”

“…There usually exists a lot of nucleation sites in perovskites, which make the average size of the crystalline grains relatively small. 35 The average size of the grains in perovskite films without GQDs ranged from 50 to 200 nm (Figure 2a), but by incorporating the GQDs, it increased to ∼400 nm (Figure 2b). The size increase of the crystallites with the GQDs can be described as follows.…”

“…These results suggest that the enhanced stabilities of the TETA-GR/WS 2 /h-BN/ MAPbI 3 :GQDs/PTAA/Au PDs are believed to result from the high chemical stability and flexibility of the constituent 2D materials�TETA-GR, WS 2 , h-BN, and GQDs�as previously reported. 25,35,59,60 ■ CONCLUSIONS Various 2D materials such as doped GR, GQDs, WS 2 , and h-BN were successfully employed to develop a TETA-GR/WS 2 / h-BN/MAPbI 3 :GQDs/PTAA/Au PD structure with the following roles: doped GR as a TCE, WS 2 as an ETL, h-BN as a blocking layer, and GQDs as a structure-controlling layer. The resulting performance of the n−i−p-type perovskite PDs was remarkably improved, particularly in their detectivity and…”

“…The difference in the surface structure was investigated for perovskite films without/with GQDs by FE-SEM (Figure a,b). There usually exists a lot of nucleation sites in perovskites, which make the average size of the crystalline grains relatively small . The average size of the grains in perovskite films without GQDs ranged from 50 to 200 nm (Figure a), but by incorporating the GQDs, it increased to ∼400 nm (Figure b).…”

“…GR quantum dots (GQDs) with advantages of fast charge extraction, high conductivity, and excellent solubility were added to perovskite films to enhance their quality, thereby improving detectivity (D*). 35 In addition, a large dark current (DC) of perovskite PDs, caused by the low barrier between the interfaces, should decrease for further improvements of the performance. For this, 2D insulators are very useful as an intermediate layer between the interfaces.…”