Cesium Lead Inorganic Solar Cell with Efficiency beyond 18% via Reduced Charge Recombination

Abstract

the main concern for degrading the device stability; for example, CH 3 NH 3 PbI 3 could be decomposed into lead Iodide (PbI 2 ) and CH 3 NH 3 I, and the organic molecules could be vapored under thermal or humidity environment. [15] Therefore, addressing the long-term stability is a primary concern for the perovskite solar cells community. [16] As an alternative, all-inorganic perovskites (CsPbX 3 , X = I, Br, Cl, or their mixtures), prized for their excellent thermal stability, have received increasing attention. [17][18][19][20][21][22][23] Among them CsPbI 3-x Br x with the band gap of around 1.73 eV showed promising, by stabilizing the α-phase, control growth of the perovskite layer, and also the interface engineering, significant progresses have been achieved. For example, Luther et al. have shown CsPbI 3 quantum dot solar cells with the efficiency of 10.77% and 13.4%, subsequently. [24,25] Our group has developed a solvent controlled growth of CsPbI 3 in dry environment, and showed a 14.67% certificated efficiency with 500 h light-soaking stability. [26] Li et al. invented a novel gradient thermal annealing to control the growth of CsPbI 2 Br film (band gap = 1.92 eV), and a champion PCE of 16.07% with a V OC of 1.23 V was realized. [27] Recently, an outstanding efficiency of 17.06% with V OC of 1.1 V was realized by Zhao et al. via using HPbI 3 as a precursor combined with the PTABr surface modification. [28] Although there are significant progresses in inorganic perovskite solar cells, the PCE is still far behind the hybrid PSCs, even compared with the I-Br mixed hybrid perovskite with a similar band gap (1.75 eV). [29] It can be found that the opencircuit voltage loss (V oc loss) is still the main reason of low performance of inorganic perovskite solar cells, which strongly related to energy band matching and defects at the interface or in the bulk of perovskite. [10,14] Most recently, Yip et al. applied PN4N as cathode interlayer to reduce the work function of the SnO 2 electron transporting layer (ETL) for tuning the electron extraction property and combing with poly[5,5′-bis(2-butyloctyl)-(2,2′-bithiophene)-4,4′-dicarboxylate-alt-5,5′-2,2′-bithiophene] (PDCBT) as hole transporting layer, leading to a significant enhancement in V OC of the CsPbI 3-x Br x PVSCs from 1.06 to 1.3 V [30] ; however, the V oc loss is still as high as 0.62 V .Here, we develop an inorganic shunt-blocking layer lithium fluoride (LiF) between SnO 2 and CsPbI 3-x Br x perovskites, which push forward the conduction band of the electron transport Cesium-based inorganic perovskite solar cells (PSCs) are promising due to their potential for improving device stability. However, the power conversion efficiency of the inorganic PSCs is still low compared with the hybrid PSCs due to the large open-circuit voltage (V OC ) loss possibly caused by charge recombination. The use of an insulated shunt-blocking layer lithium fluoride on electron transport layer SnO 2 for better energy level alignment with the conduction band minimum of the CsPbI...

Identifying Photoinduced Dipolar Polarization and Orbit–Orbit Interaction between Excitons in Organic–Inorganic Hybrid Perovskites

“…Organic-inorganic hybrid perovskites have been heavily investigated owing to their remarkable photovoltaic performance and low-cost solution processability. [1][2][3][4][5] Perovskites with ABX 3 structure are typically composed of organic cations at A site and inorganic cages BX 6 (B = Pb 2+ , Sn 2+ ; X = I − , Br − , Cl − ). [6,7] Owing to the small rotational energy and nonspherical nature, the organic cations with intrinsic dipole moment induce a dipolar polarization.…”

Recent Advances in Improving Phase Stability of Perovskite Solar Cells

“…The resulting champion device based on CsPbI 3− x Br x with a bandgap of 1.77 eV demonstrate excellent performance with the V OC as high as 1.25 V and an efficiency up to 18%. Furthermore, The device still remained 94% of the initial PCE under continuous 1 sun equivalent illumination over 1000 h, [ 52,63 ] which was the highest efficiency of CsPbI 3− x Br x PSCs reported at present.…”

Interfacial Modification through a Multifunctional Molecule for Inorganic Perovskite Solar Cells with over 18% Efficiency

“…Recently, several strategies have been reported on improving the V OC and FF of CsPbI 3 ‐based PVSCs, including vacuum thermal coevaporation, solvent‐controlled growth, dimension engineering, B‐site doping/alloying, additive loading, and so on. However, the V OC deficit and FF loss are mainly caused by the defects in bulk and surface/grain boundaries of inorganic perovskites and the mismatch of energy bands between perovskite and charge‐transporting layer (CTL) . Therefore, it would be ideal if novel dual‐functional materials can be applied to simultaneously passivate perovskite surface and promote better energy alignment to improve PVSC performance.…”