In Situ Growth of MAPbBr₃ Nanocrystals on Few‐Layer MXene Nanosheets with Efficient Energy Transfer

Abstract

PVs) [1] and optoelectronic devices. [2] The power conversion efficiencies (PCE) of perovskite solar cells have exceeded 25% [3] in a few years since the first perovskite photovoltaics with a PCE of 3.9% came out in 2009. [4] The remarkable performance is attributed to the superior properties of perovskites such as a high and balanced carrier mobility, [5] long carrier diffusion length, [6] and large light absorption coefficient in the UV-vis range. [7] Meanwhile, metal halide perovskites in the form of colloidal nanocrystals (NCs) have drawn considerable attention in recent years. [8] Perovskite NCs could be easily synthesized at room temperature and ambient conditions with a large yield. [9] Besides, these colloidal perovskite NCs feature a number of advantages such as a high photoluminescence (PL) quantum yield, [10] narrow-band emission, [11] and tunable emission over the whole visible region. [12] Benefiting from these fascinating characteristics, perovskite NCs present promise in applications such as solutionprocessed photodetectors, [13] light-emitting diodes, [14] and solar cells. [15] Perovskite NCs have also been reported to demonstrate potential as photocatalysts due to the proper energy band structure, excellent visible-light responses, and high specific surface area. [16] Nevertheless, due to the presence of large amount of crystal boundaries in NCs film that greatly restricted charge and/or energy transfer, [17] improvement of photogenerated carriers transfer at the NC interface is necessary for applications such as photoelectric conversion and photocatalysis. [16b,18] Recently, heterostructures based on perovskites NCs and 2D materials (black phosphorus, reduced graphene oxide, graphitic carbon nitride, hexagonal boron nitride, and so on) have attracted much attention. [16b,18a,19] Due to the effective protection afforded by 2D nanosheets, the stability of perovskite NCs against air, moisture, and thermal conditions has been significantly enhanced. [19e,f ] Moreover, 2D nanosheets act not only as flexible substrates that connect dispersed perovskite nanocrystals but also enable the effective charge and/or energy transfer transport through the heterostructure interfaces. For example, Xu and co-workers reported the decoration of CsPbBr 3 NCs on porous g-C 3 N 4 nanosheets to construct the composite photocatalysts via N-Br chemical bonding. [19c] The unique N-Br bonding state leads to enhanced charge separation between the two materials. As expected, the resultant composite photocatalyst The performance of perovskite nanocrystals (NCs) in optoelectronics and photocatalysis is severely limited by the presence of large amounts of crystal boundaries in NCs film that greatly restricts energy transfer. Creating heterostructures based on perovskite NCs and 2D materials is a common approach to improve the energy transport at the perovskite/2D materials interface. Herein, methylamine lead bromide (MAPbBr 3 , MA: CH 3 NH 3 + ) perovskite NCs are homogeneously deposited on highly conductive few-layer MX...

Activation Strategy of WS2 as an Efficient Photocatalytic Hydrogen Evolution Cocatalyst through Co2+ Doping to Adjust the Highly Exposed Active (100) Facet

“…[ 56 ] In contrast, the shortened PL decay lifetime indicates the faster photoinduced electron transfer (PET) from CZS to Co–WS 2 or WS 2 . The PET rate ( k T ) was estimated by the following equation [ 57 ] where k T is the specific rate constant for the charge injection process, t cp is emission lifetime for the 7% WS 2 /CZS and 7% (Co–WS 2 )/CZS, t pr is emission lifetime for the pristine CZS. The calculated results indicate that the k T at the interface of 7% WS 2 CZS was , whereas the k T further increased to for 7% (Co–WS 2 ) CZS.…”

MXenes for Solar Cells

“…Recently, Zhang et al reported surface decoration of MAPbBr 3 nanocrystals by few-layer Ti 3 C 2 T x MXene nanosheets to form the perovskite/MXene heterostructure via in situ solution growth, as shown in Fig. 2 c [ 59 ]. The facilitated electron injection from the MAPbBr 3 nanocrystals to the Ti 3 C 2 T x MXene because of the matched energy levels, as indicated in Fig.…”

Application of MXenes in Perovskite Solar Cells: A Short Review

“…In 2020, Zhang and group reported the synthesis of MAPbBr 3 nanocrystals (NCs) on the surface of few-layer MXene (Ti 3 C 2 T x ) nanosheets forming heterostructures employing an in situ solution growth method [ 70 ]. The heterostructures, ensured efficient electron injection from the MAPbBr 3 NCs to the Ti 3 C 2 T x MXene because of the well aligned energy levels.…”