Ligand-Length Modification in CsPbBr3 Perovskite Nanocrystals and Bilayers with PbS Quantum Dots for Improved Photodetection Performance

Abstract

<jats:p>Nanocrystals surface chemistry engineering offers a direct approach to tune charge carrier dynamics in nanocrystals-based photodetectors. For this purpose, we have investigated the effects of altering the surface chemistry of thin films of CsPbBr3 perovskite nanocrystals produced by the doctor blading technique, via solid state ligand-exchange using 3-mercaptopropionic acid (MPA). The electrical and electro-optical properties of photovoltaic and photoconductor devices were improved after the MPA ligand exchange, mainly because of a mobility increase up to 5 × 10−3 cm 2 / Vs . The same technology was developed to build a tandem photovoltaic device based on a bilayer of PbS quantum dots (QDs) and CsPbBr3 perovskite nanocrystals. Here, the ligand exchange was successfully carried out in a single step after the deposition of these two layers. The photodetector device showed responsivities around 40 and 20 mA/W at visible and near infrared wavelengths, respectively. This strategy can be of interest for future visible-NIR cameras, optical sensors, or receivers in photonic devices for future Internet-of-Things technology.</jats:p>

P-type Charge Transport and Selective Gas Sensing of All-Inorganic Perovskite Nanocrystals

“…Even though the implementation of Ag doping has been demonstrated to improve the thin film conductivity, the FET mobility in Ag-doped CsPbBr 3 NCs film remains moderate (8 × 10 –4 cm 2 V –1 s –1 ) . Another work on hot-injection synthesized CsPbBr 3 NCs also demonstrated unsatisfied FET mobility of 5 × 10 –7 cm 2 V –1 s –1 . Furthermore, like other nanomaterials, perovskite NCs have large specific surface areas, which may enable sensing devices beyond solar cells and LEDs.…”

Purcell Enhancement and Wavelength Shift of Emitted Light by CsPbI3 Perovskite Nanocrystals Coupled to Hyperbolic Metamaterials

“… 13 − 19 Recently, fully inorganic perovskite nanocrystals (PNCs) of cesium lead halides (CsPbX 3 , X = Cl, Br, I) were synthesized with precise size and compositional control, tunable, narrow-band emission, and high photoluminescence quantum yield (PLQY) over the whole visible wavelength range. 20 − 25 At the level of single nanocrystals, LHPs can be also potential candidates for single photon sources. 26 − 31 For quantum information applications, it is important to increase the photon emission rate (or radiative rate) of a QE, which is commonly achieved by embedding single photon nanomaterials into optical microcavities.…”

Efficient Hole Transfer via CsPbBr3 Quantum Dots Doping toward High‐Performance Organic Solar Cells

“…The CsPbBr 3 PQDs were synthesized following a hot-injection method according to previous reports. [44,45] To compare the stability of CsPbBr 3 PQDs-doped OSCs with those of the CsPbI 3 PQDs-doped counterparts, we also synthesized CsPbI 3 PQDs as described in the Experimental Section. The synthesized CsPbBr 3 and CsPbI 3 PQDs show an average size of 8.8 and 9.5 nm, respectively, according to the transmission electron microscopy (TEM) characterization (Figure 1c,d), results that are consistent with literature reports.…”

“…The synthesized CsPbBr 3 and CsPbI 3 PQDs show an average size of 8.8 and 9.5 nm, respectively, according to the transmission electron microscopy (TEM) characterization (Figure 1c,d), results that are consistent with literature reports. [43,44] The UV-vis absorption and PL intensity spectra of PQDs solutions are shown in Figure 1e,f. The absorption edge of CsPbBr 3 PQDs is 517 nm, and the optical bandgap is estimated as 2.4 eV.…”

“…The lowest unoccupied molecular orbital (LUMO) energy levels of PM6, Y6-BO, and CsPbBr 3 PQDs are À3.6, À4.1, and À3.1 eV, with the highest occupied molecular orbital (HOMO) energy levels being À5.4, À5.7, and À5.5 eV, respectively. [44,52] The energy-level diagram shows the formation of asymmetric cascade alignment of HOMO levels in the active layer, suggesting that the incorporation of CsPbBr 3 PQDs has the potential to bridge the hole transfer process from Y6-BO to PM6 and reduce charge recombination. [42] To shine light on the effect of adding CsPbBr 3 PQDs toward the photon-to-electricity conversion process of the PM6:Y6-BO OSC, PL spectra (excited at 532 nm) of PM6:Y6-BO blend film with and without CsPbBr 3 PQDs addition were measured.…”