The Role of Dimensionality on the Optoelectronic Properties of Oxide and Halide Perovskites, and their Halide Derivatives

Abstract

Halide perovskite semiconductors have risen to prominence in photovoltaics and light‐emitting diodes (LEDs), but traditional oxide perovskites, which overcome the stability limitations of their halide counterparts, have also recently witnessed a rise in potential as solar absorbers. One of the many important factors underpinning these developments is an understanding of the role of dimensionality on the optoelectronic properties and, consequently, on the performance of the materials in photovoltaics and LEDs. This review article examines the role of structural and electronic dimensionality, as well as form factor, in oxide and halide perovskites, and in lead‐free alternatives to halide perovskites. Insights into how dimensionality influences the band gap, stability, charge‐carrier transport, recombination processes and defect tolerance of the materials, and the impact these parameters have on device performance are brought forward. Particular emphasis is placed on carrier/exciton‐phonon coupling, which plays a significant role in the materials considered, owing to their soft lattices and composition of heavy elements, and becomes more prominent as dimensionality is reduced. It is finished with a discussion of the implications on the classes of materials future efforts should focus on, as well as the key questions that need to be addressed.

Elucidating the effect of Vx doped LaFe1−xO3 for advanced optical, spintronic, and thermoelectric devices

“…TE parameters show that LFO, V 0.25 -LFO, and V 0.75 -LFO prefer a hole as a charge carrier, whereas in V 0.5 -LFO the carrier mobility can switch between hole and electron and LVO recognizes the electron as a charge carrier. All present compounds are categorized as p-type doping due to their positive n value which is consistent with the reports of Hoye et al [41]. The calculated TE parameters predict that the present compounds, especially V 0.25 -LFO and V 0.5 -LFO own useful TE attributes and can be used in the thermal sensors or generator.…”

Epitaxial Growth of Lead‐Free 2D Cs3Cu2I5 Perovskites for High‐Performance UV Photodetectors

“…[53] For 2D Cs 3 Cu 2 I 5 , the exciton binding energy is ≈40 meV, calculated via fitting integrated PL intensity as a function of reciprocal temperature (Figure 3d); this value is lower than that of 0D Cs 3 Cu 2 I 5 , principally because low dimensionality could facilitate the formation of selftrapped excitons. [27,54,55] Carrier recombination dynamics of the Cs 3 Cu 2 I 5 flakes was further investigated through transient-state PL measurements. The PL decay trace (450 nm) was strictly fitted with a single-exponential mode, generating an average lifetime of ≈1047 ns, which is much larger than carrier recombination lifetime observed in conventional lead-halide perovskites (a few or dozens of nanoseconds normally).…”

Femtosecond Exciton and Carrier Relaxation Dynamics of Two-Dimensional (2D) and Quasi-2D Tin Perovskites

“…As a consequence, the overlap between the two orbitals also decreases. 17,18 To obtain the greatest power conversion efficiencies (PCEs) from a 3D Sn PSC, purification of Sn precursors, 19,20 complexation of Sn precursors with dimethyl sulfoxide, 20−22 two-step crystallization, 23,24 additives, 25−28 and mixed cationic structures 29,30 were reported for preparations of Sn perovskite thin-film samples.…”

“…The use of LD structures such as 2D and quasi-2D phases in tin perovskite solar cells (PSCs) has proven to be advantageous as they can enhance their stability through passivating the Sn vacancies and suppressing the self-doping due to oxidation of Sn 2+ to Sn 4+ , an enduring problem in three-dimensional (3D) Sn PSCs. ,,− The reasons for Sn vacancies and self-oxidation of Sn atoms were explained as being due to a strong antibonding coupling between Sn (5s) and I (6p) orbitals, which is weaker in LD structures because orbitals are localized through confinement effects. As a consequence, the overlap between the two orbitals also decreases. , To obtain the greatest power conversion efficiencies (PCEs) from a 3D Sn PSC, purification of Sn precursors, , complexation of Sn precursors with dimethyl sulfoxide, − two-step crystallization, , additives, − and mixed cationic structures , were reported for preparations of Sn perovskite thin-film samples.…”