Shape‐ and Trap‐Controlled Nanocrystals for Giant‐Performance Improvement of All‐Inorganic Perovskite Photodetectors

Abstract

In the last few years, all‐inorganic perovskite CsPbBr3 nanocrystals (NCs) have attracted tremendous attention for its high carrier mobility, long carrier diffusion length, excellent visible light absorption, and more importantly superior air stability. In fact, photodetectors (PDs) are designed and fabricated using the CsPbBr3 NCs with very high performance. Herein, by optimizing the NC shape, size, and surface passivation, the CsPbBr3 PDs are developed with an even higher performance. It is found that the PDs based on CsPbBr3 nanoribbons show the best photoresponse among all common NC structures synthesized. Moreover, it is found that 6,6‐phenyl‐C61‐butyric acid ethyl ester can be used to passivate defects on the CsPbBr3 nanoribbon surface and shows the charge transfer. As a result, the device displays superior photoresponsivity (R = 18.4 A W−1), excellent signal‐to‐noise ratio, as high as 104, and a very sharp rise/decay time (8.7/3.5 ms). The method demonstrated may offer an attractive strategy to improve sensitivity for all‐inorganic perovskite PDs in general.

Iodine‐Optimized Interface for Inorganic CsPbI2Br Perovskite Solar Cell to Attain High Stabilized Efficiency Exceeding 14%

“…Moreover, there are also reports suggesting that the A site does not confer any fundamental advantage to the charge carrier mobilities . Hence, it is desirable to replace the fragile organic group with more robust inorganic Cs cations to form more stable CsPb X 3 perovskite material . In fact, there have been studies of CsPb X 3 in terms of its compositional and structural phase stability .…”

“…[22][23][24][25] Hence, it is desirable to replace the fragile organic group with more robust inorganic Cs cations to form more stable CsPbX 3 perovskite material. [26][27][28][29][30][31] In fact, there have been studies of CsPbX 3 in terms of its compositional and structural phase stability. [32][33][34] Unfortunately, this Cs replacement brings about a different problem: The desired black CsPbI 3 cubic phase (with narrow bandgap of 1.7 eV) is not the most thermodynamically stable phase at normal operational temperatures, and it may turn into the nonperovskite yellow phase quickly, even in an inert atmosphere.…”

Synergy of Hydrophobic Surface Capping and Lattice Contraction for Stable and High‐Efficiency Inorganic CsPbI2Br Perovskite Solar Cells

“…But along with their advantages, the deficiencies were quickly exposed: even though CsPbBr 3 shows good thermal stability, its band gap is as large as 2.3 eV, too large to absorb visible light beyond 540 nm. [17][18][19] Although CsPbI 3 has a more suitable band gap (1.73 eV), it suffers from notorious phase instability. [20][21][22] Later, the dual halide CsPbI 2 Br was developed, and it has great advantages in terms of ambient phase stability and a more suitable band gap (1.91 eV).…”

Strategies toward High‐Performance Solution‐Processed Lateral Photodetectors

“…The optimized device presented R of 10.85 A W −1 , D* of 3.06 × 10 13 Jones, rise/decay times of 44/390 µs, and LDR of 73 dB. Meanwhile, Pang et al synthesized CsPbBr 3 nanocrystals with different shapes, and introduced PCBM to fabricate PDs (see Figure c,d) . They found that the device based on nanoribbons showed better performance compared with those based on QDs and nanocubes, and this could be attributed to the higher mobility and fewer defects.…”

“…Copyright 2017, The Royal Society of Chemistry. c,d) Reproduced with permission . Copyright 2017, Wiley‐VCH.…”