Pressure‐Induced Bandgap Optimization in Lead‐Based Perovskites with Prolonged Carrier Lifetime and Ambient Retainability

Abstract

Bond length and bond angle exhibited by valence electrons is essential to the core of chemistry. Using lead‐based organic–inorganic perovskite compounds as an exploratory platform, it is demonstrated that the modulation of valence electrons by compression can lead to discovery of new properties of known compounds. Yet, despite its unprecedented progress, further efficiency boost of lead‐based organic–inorganic perovskite solar cells is hampered by their wider bandgap than the optimum value according to the Shockley–Queisser limit. By modulating the valence electron wavefunction with modest hydraulic pressure up to 2.1 GPa, the optimized bandgap for single‐junction solar cells in lead‐based perovskites, for the first time, is achieved by narrowing the bandgap of formamidinium lead triiodide (HC(NH2)2PbI3) from 1.489 to 1.337 eV. Strikingly, such bandgap narrowing is partially retained after the release of pressure to ambient, and the bandgap narrowing is also accompanied with double‐prolonged carrier lifetime. With First‐principles simulation, this work opens a new dimension in basic chemical understanding of structural photonics and electronics and paves an alternative pathway toward better photovoltaic materials‐by‐design.

Performances Enhancement in Perovskite Solar Cells by Incorporating Plasmonic Au NRs@SiO2 at Absorber/HTL Interface

“…Benefiting from their excellent band alignment, the PSCs show much lower photon energy loss with a relative large ratio of about 0.80 for open‐circuit voltage ( V oc )/band gap ( E g ), in comparison to the typical value of 0.60 for other types of solar cells . The reported V oc of CH 3 NH 3 PbI 3 /spiro‐OMeTAD based PSCs is close to its theoretical value of 1.33 V according to Shockley–Queisser limitation …”

Pressure‐Induced Broadband Emission of 2D Organic–Inorganic Hybrid Perovskite (C6H5C2H4NH3)2PbBr4

“…[1] 2D organic-inorganic metal halide perovskites possess a layered sandwich structure composed of alternating organic and inorganic components, giving rise to remarkable quantum confinement effects and large exciton binding energy, in which the generated carries are confined within the inorganic layers. [10] The electronic conductivity of halide perovskite can be greatly enhanced with compression. [2] The bulky phenyl ethylammonium (PEA) organic molecule spacer cation is applied to synthesize 2D or quasi-2D Ruddlesden-Popper lead bromide mild pressure.…”

Pressure‐Induced Structural Evolution and Bandgap Optimization of Lead‐Free Halide Double Perovskite (NH4)2SeBr6

“…For example, we have experimentally investigated the high‐pressure effect on the properties of organic–inorganic lead halide perovskite CH(NH 2 ) 2 PbBr 3 , and found that its structure undergoes two phase transitions below 2.2 GPa, directly leading to the red shift/blue shift of bandgap and the variation of the colors . Strikingly, upon applying pressure of up to 2.1 GPa, the bandgap of CH(NH 2 ) 2 PbI 3 is reported to experience a red shift from 1.489 to 1.337 eV, which exactly reaches to the optimal bandgap required by Shockley–Queisser efficiency limit . Meanwhile, Jia et al found that CH 3 NH 3 SnI 3 can possess structural stability, increased electrical conductivity, and enhanced photo responsiveness via two sequential compression and decompression cycles .…”