In‐Situ Hot Oxygen Cleansing and Passivation for All‐Inorganic Perovskite Solar Cells Deposited in Ambient to Breakthrough 19% Efficiency

Abstract

All-inorganic perovskite CsPbI 3 has attracted extensive attention recently because of its excellent thermal and chemical stability. However, its photovoltaic performance is hindered by large energy losses (E loss ) due to the presence of point defects. In addition, hydroiodic acid (HI) is currently employed as a hydrolysis-derived precursor of intermediate compounds, which often leads to a small amount of organic residue, thus undermining its chemical stability. Herein, an in-situ hot oxygen cleansing with superior passivation (HOCP) for the triple halide-mixed CsPb(I 2.85 Br 0.149 Cl 0.001 ) perovskite solar cells (abbreviated as CsPbTh 3 ) deposited in an ambient atmosphere to reduce the E loss to as low as 0.48 eV for the power conversion efficiency (PCE) to reach 19.65% is demonstrated. It is found that the hot oxygen treatment effectively removes the organic residues. Meanwhile, it passivates halide vacancies, hence reduces the trap states and nonradiative recombination losses within the perovskite layer. As a result, the PCE is increased significantly from 17.15% to 19.65% under 1 sun illumination with an open-circuit voltage enlarged to 1.23 from 1.14 V, which corresponds to an E loss reduction from 0.57 to 0.48 eV. Also, the HOCP-treated devices exhibit better long-term stability. This insight should pave a way for decreasing nonradiative charge recombination losses for high-performance inorganic perovskite photoelectronics.

Highly Efficient and Stable CsPbTh3 (Th = I, Br, Cl) Perovskite Solar Cells by Combinational Passivation Strategy

“…The fast and slow time constants for the photobleaching peaks of the CsPbTh 3 film with CPS are longer than the pristine CsPbTh 3 film without CPS, indicative of suppressed recom-bination dynamics of electron-hole pairs within CPS-CsPbTh 3 film. [31,53] We next quantify the defect in the perovskite layer through space charge limited current (SCLC) method. A typical electrononly device structure on FTO/TiO 2 /CPS-CsPbTh 3 /[6,6]-Phenyl-C61-butyric acid methyl ester (PCBM)/Ag was fabricated to measure dark I-V curves.…”

“…Based on our recent studies, the CsPbTh 3 film exhibited higher crystallinity than the pure CsPbI 3 film and achieved outstanding photovoltaic performance. [ 31 ] In this case, the CPS was performed on the CsPbTh 3 perovskite film, which significantly enhanced the quality of perovskite film due to the synergistic passivation effect of GA + , Ac − , and GCA. We first investigate the effect of GA + concentration on the crystal structure of CsPbTh 3 films.…”

“…We recently found that incorporating a small amount of Br and Cl into CsPbI 3 film (marked as CsPbTh 3 ) exhibited an optimized carrier dynamics performance than pure CsPbI 3 perovskite due to their higher electronegativity and ionization potential than I. [31] Also, Ma et al reported that introducing Br and Cl into the CsPbI 3 framework can regulate nucleation, crystallization kinetics, and orientational order within the bulk film. Therefore, the CsPbTh 3 PSCs achieved a high PCE of 17.14% with an energy loss of 0.6 eV and enhanced phase stability.…”

Design of all-inorganic hole-transport-material-free CsPbI3/CsSnI3 heterojunction solar cells by device simulation

“…Many strategies have been developed to fabricate thermodynamically stabilized CsPbI 3 solar cell and to improve cell efficiency. CsPbI 3 solar cells with PCE over 19% have been reported by several groups [10][11][12].…”

“…Due to a suitable bandgap and good tolerance to humidity, oxygen and thermal stress, CsPbI 3 shows great prospect for stable PSCs. The CsPbI 3 solar cell has been a rapid growing research field and impressive progresses have been made [9][10][11][12]. Many strategies have been developed to fabricate thermodynamically stabilized CsPbI 3 solar cell and to improve cell efficiency.…”