Professor Zang Zhigang's team at Chongqing University published a research paper titled "Iodide Management and Oriented Crystallization Modulation for High-Performance All-Air Processed Perovskite Solar Cells" in the journal Advanced Materials. Team member Yang Haichao is the first author, and Professor Zang Zhigang is the corresponding author.

Key Highlight: This paper proposes a buried interface optimization strategy, achieving the highest PCE (25.13%) and high open-circuit voltage (1.191 V) for an all-air-processed device (Rb0.02(FA0.95Cs0.05)0.98PbI2.91Br0.03Cl0.06).

Halide-related defects at buried interfaces not only induce nonradiative recombination but also severely impact the long-term stability of perovskite solar cells (PSCs). To address these challenges, the research group led by Professor Zang Zhigang of Chongqing University proposed a bottom-up, integrated modification strategy involving the multi-site antioxidant ergothioneine (EGT) to optimize the buried interface of perovskites, thereby managing iodide ions and manipulating crystallization dynamics. The optimized all-air-processed device (Rb0.02(FA0.95Cs0.05)0.98PbI2.91Br0.03Cl0.06) achieved a power conversion efficiency (PCE) of 25.13%, one of the highest values for air-processed devices. It also exhibited an ultra-high open-circuit voltage (VOC) of 1.191 V and a fill factor (FF) of 84.9%. The optimized unpackaged device exhibited strong humidity, thermal, and operational stability under the ISOS protocol. Specifically, the device maintained an initial efficiency of 90.12% after 1512 hours of thermal aging at 65°C and 90.14% after 930 hours of continuous maximum power point tracking (MPPT) under simulated AM1.5 illumination.

Figure 1. a) Diagrammatic representation of the mechanism for defect formation and passivation through EGT modification. b) Electron mobility of the pristine SnO₂ and EGT-modified SnO₂. Conductive AFM images of c) SnO₂ and d) SnO₂/EGT. e) Sn 3d XPS spectra of SnO₂ and SnO₂/EGT films. XPS spectra of O 1s for f) pristine SnO₂ and g) EGT-modified SnO₂ films. h) ¹³C NMR spectra of SnO₂ solutions containing EGT and pure EGT. FTIR spectra in the wavenumber ranges of i) 2250–2450 cm⁻¹ and j) 1550–1700 cm⁻¹ of SnO₂, SnO₂ mixed with EGT and pure EGT.

Figure 2. a) Pb 4f and b) I 3d XPS spectra of the control and EGT-modified perovskite. c) FTIR spectra of PbI₂, PbI₂ combined with EGT and pure EGT in the region of 1520−1750 cm⁻¹. GIXRD patterns of the perovskite films prepared on d) SnO₂ and e) SnO₂/EGT. f) Dependence of the d-spacing values on grazing incidence angle of perovskite films. GIWAXS patterns of the g) control and h) EGT-modified perovskite films. In situ PL analyses of the control perovskite films over i) spinning and j) annealing process. In situ PL analyses of the EGT-modified perovskite films over k) spinning and l)

annealing process. In situ UV–vis absorption measurements of the m) control and n) EGT-modified perovskite films during the annealing process. XRD patterns of o) control and p) EGT-modified perovskite films with different annealing times.

Figure 3. a) Photographs of FAI solutions and FAI powders without and with EGT that were aged under ambient conditions. UV–vis absorption spectra of b) pure FAI and c) FAI containing EGT that were aged under ambient conditions. d) UV–vis absorption spectra of I₂ and I₂ with EGT. FTIR spectra of I₂, I₂ with EGT, and pure EGT in the regions of e) 3050‒3250 cm⁻¹ and f) 1450‒1750 cm⁻¹. g) Pb 4f XPS spectra of aged perovskite films. UV–vis absorbance spectra of the toluene soaked with h) control and i) EGT-modified perovskite films exposed to light soaking and 65 °C heating treatment. j) TGA plots of weight loss of perovskite without and with EGT.

Figure 5. a) PL and b) TRPL spectra of the perovskite films prepared on glass or glass/EGT. PL mapping measurements of the perovskite films deposited on c) glass or d) glass/EGT. e) PL and f) TRPL spectra of the perovskite films based on ITO/SnO₂ or ITO/SnO₂/EGT. PL mapping images of the perovskite films synthesized on SnO₂ g) without or h) with EGT modification. i) PLQY of perovskite films. j) Transient photovoltage decay curves of the devices based on SnO₂ or SnO₂/EGT. k,l) SCLC versus voltage of the electron-only devices. m) Energy level diagram of each part in the device. n) Transient photocurrent decay measurements of both devices. o) Nyquist plots of the PSCs based on SnO₂ and SnO₂/EGT. p) Mott–Schottky analysis of the devices.

Figure 6. a) Normal distribution of the PCEs for the devices without or with EGT modification, consisted of twenty independent cells for each device. b) J–V curves of the champion devices based on SnO₂ or SnO₂/EGT. c) J–V curves of the champion EGT-modified device with PEAI post-treatment. d) J–V curves of the target device with an active area of 1 cm². e) Steady-state output measurements for the champion PSCs without or with EGT modification. f) IPCE spectra of the best-performing device. g) Humidity stability of the unencapsulated devices under an ambient environment with 30 ± 5% RH. h)

Thermal stability of the unencapsulated devices heated at 65 °C. i) Operational stabilities of the unencapsulated PSCs at maximum power point under one-sun illumination at 25 ± 5 °C.

Figure 7. a) Photo images of perovskite films aged for12 days under 65% RH. UV–vis absorption spectra of b) control and c) target perovskite films after ageing at 65% RH for different times. XRD patterns of d) control and e) target perovskite films after ageing at 65% RH for different times. SEM images of f) control and g) EGT-modified perovskite films heated at 65 °C and under continuous one-sun illumination for 10 h.