Probing Strain-Induced Effects on Performance of Low-Dimensional Hybrid Perovskites for Solar Energy Harvesting

Abstract

The application of strain to photovoltaics (PVs), thermoelectrics (TEs), and semiconductors often has substantial impacts on the fundamental properties governing the efficiency of these materials. In this work, we investigate two stable phases of hybrid organic–inorganic two-dimensional (2D) perovskites (2DPKs) and their response to the application of tensile and compressive strain of up to 5%. These 2D MAPbI3 analogues are known to exhibit strongly anisotropic properties and have been put forward as excellent candidates for application in mixed PV–TE devices. Our results, stemming from ab initio density functional theory calculations and investigation of transport properties through the Boltzmann transport equations, further elucidate the key properties contributing to the success of these materials. In particular, both the M1 and M2 phases exhibit stable structures between −5 and 5% biaxial strains. The M2 phase exhibits an excellent 23.8% power conversion efficiency under the application of 5% tensile strain. Furthermore, we analyze the effects of spin-orbit coupling on the band structures of both phases, revealing great potential for spintronic applications with the M2 phase, demonstrating Rashba coefficients up to 3.67 eV Å.

Atomistic Description of the Impact of Spacer Selection on Two-Dimensional (2D) Perovskites: A Case Study of 2D Ruddlesden–Popper CsPbI3 Analogues

“…In Figure S4, we compute the band structure more densely along the X−Γ–Y path, where the hallmark of Rashba split bands can be clearly seen, with the shifting of the vertex of the split bands away from the Γ point, together with the inverted spin character of the VBM/CBM as the X−Γ–Y path is traversed. As we have noted in our previous work, Rashba splitting is very sensitive to geometric changes in the perovskite system owing to the strong spatially localized effects of SOC . This paves the way for modulating the nature of excitations that are mediated by direct photoexcitation in the visible range, as demonstrated by Wang et al The correspondence between spatial and electronic degrees of freedom can even be seen in the case of ThFA, where the Γ–Y direction exhibits significantly stronger Rashba spin splitting than the Γ–X direction, in direct relation to the strong anisotropy previously discussed regarding the in-plane cell parameters.…”

“…As we have noted in our previous work, Rashba splitting is very sensitive to geometric changes in the perovskite system owing to the strong spatially localized effects of SOC. 35 This paves the way for modulating the nature of excitations that are mediated by direct photoexcitation in the visible range, as demonstrated by Wang et al 52 The correspondence between spatial and electronic degrees of freedom can even be seen in the case of ThFA, where the Γ−Y direction exhibits significantly stronger Rashba spin splitting than the Γ−X direction, in direct relation to the strong anisotropy previously discussed regarding the in-plane cell parameters.…”

“…2DPKs exhibit significantly improved stability compared to that of their bulk counterparts, but this often comes at the cost of PV performance because of significantly increased band gaps . Thus, to generate stable perovskite solar cells with favorable optoelectronic performance, research involving 2DPKs aims to balance these two factors while simultaneously exploiting properties available exclusively to the 2D materials, such as the Rashba effect. − Additionally, the choice of the A′ spacing cation has been shown to affect characteristics ranging from the ease of synthesis and resultant crystal orientations to phase stability and even optoelectronic performance. − In this Letter, we characterize the role of this A′ spacing cation to further elucidate its effects on the resulting geometry, electronic structure, and thermoelectric (TE) and PV properties of 2DRP CsPbI 3 analogues.…”

Charge Carrier Dynamics at the Interface of 2D Metal–Organic Frameworks and Hybrid Perovskites for Solar Energy Harvesting

“…Structural implications of the strain applied to the materials that is necessary to facilitate commensurate lattice parameters had little impact on the MOF and perovskite subsystems. 42 The resulting structures had an average Pb−I bond distance of 3.23 and 3.24 Å for the UMCM-309a and ZrL3 interfaced MAPbI 3 systems, respectively. Additionally, for both systems, cis and trans Pb−I−Pb bond angles center around 90°and 175°, respectively (Figure S1), which are in line with previous investigations of MAPbI 3 and its 2D analogues.…”

“…Structural implications of the strain applied to the materials that is necessary to facilitate commensurate lattice parameters had little impact on the MOF and perovskite subsystems . The resulting structures had an average Pb–I bond distance of 3.23 and 3.24 Å for the UMCM-309a and ZrL3 interfaced MAPbI 3 systems, respectively.…”