复旦大学梁佳研究员团队在Nature Communications期刊发表题为“Iodide Management and Oriented Crystallization Modulation for High-Performance All-Air Processed Perovskite Solar Cells”的研究论文，团队成员李天鹏为论文第一作者，梁佳研究员为论文通讯作者。
核心亮点：本文提出一种基于金属硫系（Sn(S0.92 Se0.08 ) 2）电子传递层，解决非铅钙钛矿（锡基钙钛矿）太阳能电池的能级不匹配导致的低VOC问题，实现非铅钙钛矿太阳能电池PCE 高达11.78% 和 高VOC （0.73 V)，且器件实现在1632 h后仍保留其初始效率的95%以上的较高稳定性。
锡基钙钛矿太阳能电池因其生物相容性、窄带隙和长热载流子寿命而受到关注。然而，n-i-p型锡基钙钛矿太阳能电池表现不佳，很大程度上是由于不加区分地使用了最初为n-i-p型铅基钙钛矿太阳能电池设计的金属氧化物电子传输层。这种性能不佳主要由两大因素造成：氧分子从氧空位中解吸，导致锡基钙钛矿中的Sn2+氧化为Sn4+，以及TiO2 ETLs的能级不匹配，导致VOC降低。为解决上述问题，复旦大学梁钾研究员团队在n-i-p型TPSCs中引入了ETL，即Sn(S0.92 Se0.08 ) 2的金属混合硫属化物。实验和理论结构均表明，Sn(S 0.92 Se0.08 ) 2 ETL不仅可以避免O2分子的解吸，还可以阻碍锡基钙钛矿中的Sn2+与空气中存在的O2之间的反应，并提供更浅的CBM位置、改善的形态、增强的导电性和增加的电子迁移率。这些特性使具有Sn(S 0.92 Se0.08 ) 2 ETL的n-i-p型TPSC的VOC显著提高，从0.48 V增加到0.73 V，并将PCE从6.98%提高到11.78%，提高了65%以上，并且这种ETL大幅提升了n-i-p型TPSC的运行稳定性。
最后，科研人员在环境条件下检查了具有TiO2、SnS2和Sn(S0.92 Se0.08 )2 ETLs的n-i-p型TPSCs的长期稳定性，封装有TiO2、SnS2和Sn(S0.92 Se0.08 )2 ETLs的n-i-p型TPSC的PCE随老化时间的变化。显然，这三种设备的退化程度有明显的不同。采用TiO2 ETL的n-i-p型TPSCs的PCE在912 h后迅速下降，在1080 h后仅保留了初始效率的40%；采用SnS2 ETL的n-i-p型TPSCs在1632 h后仍保留了初始效率的80%以上；而采用Sn(S0.92 Se0.08 )2 ETL的n-i-p型TPSC在1632 h后仍保留其初始效率的95%以上，这对实际应用意义非凡。
Fig. 1 | Oxygen vacancies in TiO2 ETLs. a) Schematic diagram of the buried interface between the TiO2 ETL and Sn-based perovskite layer. Oxygen desorption from OVs in the TiO2 ETL accelerates the oxidation of Sn2+ to Sn4+ within the Sn-based perovskite. b) EPR spectra of the TiO2 ETL, confirming the existence of OVs. c ) Highresolution XPS spectra in the O 1 s region of the TiO2 ETL, further supporting the existence of OVs. High-resolution XPS spectra of Sn-based perovskite films on (d) FTO and (e) FTO/TiO2 substrates after aging for 14 days, respectively. This distinct difference observed suggests that desorbed oxygen from TiO2 films leads to severe oxidation in Sn-based perovskites.
Fig. 2 | Metal chalcogenide ETLs. UPS spectra of VBM onset and photoemission cutoff energy boundary of (a) SnS2 and (b) Sn(S0.92Se0.08)2 ETLs. The Sn(S0.92Se0.08)2 ETL shows the shallowest CBM position, highlighting its potential as the preferred ETL candidate for nip-type TPSCs. c ) KPFM curves and images of the TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs. The scalebars are 1 μm. d) UV-vis optical transmission spectra of TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs, revealing similar optical transparency between the Sn(S0.92Se0.08)2 ETL and the TiO2 ETL throughout the spectrum. e) J-V curves at the trap-free SCLC regime of TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs, fitted with the Mott-Gurney law. The results suggest that the mobility of the Sn(S0.92Se0.08)2 ETL is an order of magnitude higher than that of the TiO2 ETL.
Fig. 3 | Strong interaction between metal chalcogenide ETLs and Sn-based perovskite layers. The electron density distribution of Sn-based perovskites interacting with (a) O2, (b) SnS2 and (c) Sn(S0.92Se0.08)2 molecules, indicating that the Sn(S0.92Se0.08)2 ETL not only circumvents O2 molecules desorption, but also inhibits the reaction between Sn2+ ions in Sn-based perovskites and O2 molecules present in air. GIWAXS patterns of the Sn-based perovskite films grown on (d) TiO2, (e) SnS2, and (f) Sn(S0.92Se0.08)2 ETLs respectively. These results indicate that the Sn(S0.92Se0.08)2 ETL induces the highest crystalline phase purity at the buried interface due to the strong interaction. g) The Sn4+/Sn2+ ratios in the Sn 3d5/2 and Sn 3d3/2 regions of the Sn-based perovskite films deposited on different ETLs, including TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs. The Sn-based perovskite with the Sn(S0.92Se0.08)2 ETL shows the lowest values, indicative of the strongest interaction between the two. h) PL and (i) TRPL spectra of Sn-based perovskite films deposited on TiO2, SnS2, and Sn(S0.92Se0.08)2 ETLs, respectively. Both results suggest the fastest electron transfer in the structure of Sn-based perovskite films deposited on Sn(S0.92Se0.08)2 films.
Fig. 4 | Photovoltaic performance of TPSCs with metal chalcogenide ETLs. a) Schematic diagram of nip-type TPSCs with the structure of FTO/ETL/Sn-based perovskite/PTAA/Ag, utilizing TiO2, SnS2, and Sn(S0.92Se0.08)2 films as ETLs. b )J–V curves of nip-type TPSCs with TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs, respectively. c) A comparison of PCE between this work and other reported PCEs (over 6.5%) of niptype TPSCs. The impressive PCE of the nip-type TPSC with the Sn(S0.92Se0.08)2 film significantly surpasses those of previously reported nip-type TPSCs with TiO2 films.d) EQE spectra and integrated Jsc values of the nip-type TPSCs with TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs, respectively. e) Nyquist plots. f dark J–V curves, and (g) stabilized power output of nip-type TPSCs with TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs respectively. These result indicate that the nip-type TPSC with the Sn(S0.92Se0.08)2 ETL showcases the reduced charge transfer resistance, fastest electron transport, and lowest defect density among the three types ETLs. h) Normalized PCE of unencapsulated nip-type TPSCs with TiO2, SnS2 and Sn(S0.92Se0.08)2 ETLs for over 1600 h in an N2 glovebox. These findings collectively support the potential of metal chalcogenide ETLs, particularly Sn(S0.92Se0.08)2, for advancing the performance and stability of nip-type TPSCs.
本文来源：DOI: 10.1038/s41467-024-53713-4
https://doi.org/10.1038/s41467-024-53713-4