Ge Incorporation to Stabilize Efficient Inorganic CsPbI₃ Perovskite Solar Cells

Abstract

extensively researched from the material to the device in the past few years; however, the power conversion efficiency (PCE) of CsPbI 3 -based solar cells still lags behind hybrid perovskite solar cells (PSCs) as well as its maximum theoretical PCE. [2] Currently, the application of CsPbI 3 in PSCs is mainly perplexed by unsatisfied CsPbI 3 film quality, including black-phase stability, defects, and crystallinity. [3] Particularly, the black-phase CsPbI 3 is moisture-induced phase instability, that is, the moisture could easily result in phase transition from black phase into unfavorable yellow non-perovskite phase at room temperature. [4] Therefore, a big challenge is stabilizing high-quality black-phase CsPbI 3 films for efficient devices.Generally, the CsPbI 3 black-phase instability is mainly due to its lower tolerance factor, that is, the small size of the Cs + could not sustain PbI 6 octahedra in the cubic α-CsPbI 3 structure, easily leading to the δ-CsPbI 3 transformation. [3,4] To stabilize the black phase of CsPbI 3 films, different methods have been attempted, such as bromide partial iodide substitution to give the CsPbI 2 Br or CsPbIBr 2 , reducing crystal sizes or introducing intermediate phases in some degree. [5] Furthermore, controllable alien element doping into CsPbI 3 films (i.e., Ca 2+ , Sn 2+ , Ge 2+ , Sr 2+ , Mn 2+ , In 3+ , Bi 3+ , etc.) could increase the tolerance factor of the CsPbI 3 in some degree. [6,7] Typically, the replacement of PbI 2 with DMAPbI 3 (HPbI 3 ) as the Pb 2+ resource has directly promoted the PCE to ≈20% along with modifying crystallinity process or introducing surface passivation. [8] Even so, severe non-radiative recombination of the CsPbI 3 is still detrimental to the cell performance and opencircuit voltage (V oc ), in the meantime, the stability of CsPbI 3 perovskite solar cells has not been fully solved yet. [1,9] In addition, unlike hybrid perovskites, post-treatment toward passivating and stabilizing the CsPbI 3 films by in situ introducing low-dimensional perovskites, has not worked well sometimes, especially for the DMAPbI 3 system. [2c,10] Obviously, it is urgent to explore effective strategies to modify CsPbI 3 perovskite crystal growth, passivate defects, and improve the anti-humidity ability of inorganic perovskite solar cells.In current work, Ge element has been firstly incorporated into CsPbI 3 perovskite solar cells based on DMAPbI 3 -based precursor systems. Our investigation reveals that Ge incorporation can modify crystallization growth of CsPb 1−x Ge x I 3 films, Aiming at stable CsPbI 3 perovskite solar cells, Ge incorporated for the first time into DMAPbI 3 -based precursor systems. Ge incorporation is found to be able to modify crystallization growth of CsPb 1−x Ge x I 3 films and reduce annealing temperature and treatment time by lowering CsPbI 3 formation energy. The champion power conversion efficiency (PCE) of 19.52% is achieved with a certified PCE of 18.8%, which is the highest performance of CsPbI 3 PSCs with alien element-dopin...

Ge Bidirectional Diffusion to Simultaneously Engineer Back Interface and Bulk Defects in the Absorber for Efficient CZTSSe Solar Cells

“…[ 21 ] In addition, X‐ray photoelectron spectroscopy (XPS) also demonstrates the Ge valence state of +4 in the GeO 2 film with two peaks at 1220 and 1255 eV assigned to the Ge2p core levels and a peak at 532 eV to the O1s core level, respectively (Figure S1b, Supporting Information). [ 22 ] Remarkably, this GeO 2 film is easily dissolved in water and hydrochloric acid, and no X‐ray diffraction (XRD) patterns of the GeO 2 are found as well, thus suggesting that the GeO 2 film is in an amorphous state. [ 23 ] The GeO 2 film thickness is determined by its concentration, which is labeled as n‐ GeO 2 ( n represents the GeO 2 concentration (g mL −1 ), n = 0, 0.04, 0.07, 0.10, and 0.13).…”

Sustainable Pb Management in Perovskite Solar Cells toward Eco‐Friendly Development

“…Furthermore, Meng et al incorporated Ge into a DMAPbI 3 -based precursor system for the first time to control the crystalline growth of CsPb 1-x GexI 3 films, thereby reducing the annealing temperature and treatment time by lowering the formation energy of CsPbI 3 and achieving a PCE with 19.52%. [161] In situ formation of GeO 2 significantly improved the moisture resistance of the perovskite film and related devices, and passivated the grain boundary and surface defects.…”

Progress in the preparation and application of CsPbX3 perovskites

“…(h) Schematic diagram of the crystallization kinetics of CsPbI 3 and Ge-doped CsPbI 3 thin films. 38 (i) J-V curves of the champion CsPb 0.95 Ge 0.05 I 3 -based PSC and control group. 38 Copyright 2021, Wiley-VCH Verlag.…”

“…38 (i) J-V curves of the champion CsPb 0.95 Ge 0.05 I 3 -based PSC and control group. 38 Copyright 2021, Wiley-VCH Verlag. (j) J-V curves of CsPbBr 3 and Eu 2+ -doped CsPbBr 3 -based PSC.…”