Tuning Lattice Structure of Ferroelastic Twin-Domains Achieving Efficient Perovskite Solar Cells
Wajid Ali,‡ Wei Qin,‡ Hao Tian, Junxue Guo, Zhaochi Feng, and Can Li*
https://pubs.acs.org/doi/10.1021/acsenergylett.3c01936
The impact of the lattice structure on photoelectronic properties of metal halide perovskites (MHP) is widely acknowledged. However, the correlation between crystallography and photogenerated charge carriers remains unclear. Herein, we report on the discrepant ferroelastic response and photoelectronic properties under direct current (DC)-poling or alternating current (AC)-poling in methylammonium lead iodide (MAPbI3) twin-domains. A preferred crystal orientation is established only under DC-poling, which leads to domain boundary evolution and enhanced light scattering. Continuous DC-poling leads to an irreversible lattice expansion of approximately 0.1%, resulting in an elevated light absorption of 10%. Consequently, under DC-poling the short-circuit current density and open-circuit voltage of the solar cell are elevated by 1.34 mA cm−2 and 135 mV, respectively. The power conversion efficiency (PCE) of poling-enhanced solar cells has reached 23.12%, representing one of the highest PCEs of MAPbI3. This work reveals that microscopic modulation of crystallographic structure profoundly impacts solar cell performance.
近日，我组在微观晶体结构对太阳电池性能的研究中取得新进展。晶格结构对金属卤化物钙钛矿光电性能的影响已得到广泛认可，然而晶体的晶体结构对光生载流子影响的微观机制仍不清楚，其原因主要在于精细、连续地调控太阳电池光吸收层的晶体结构是十分困难的。鉴于此，我组在前期发现的钙钛矿材料铁弹应变调控方法基础上（Nature Communications），揭示了直流、交变调制下铁弹应变存在的差异，实现了对甲氨铅碘（MAPbI3）材料晶体结构的精细调控。
我们的研究发现直流极化可以建立特定的择优取向，畴壁的整齐排列产生了增强的光散射。连续的直流极化会导致光吸收增加约10%，晶格产生约0.1%的不可逆膨胀，使太阳能电池的短路电流密度提高1.34 mA/cm2，开路电压提升约135 mV。铁弹应变下太阳能电池的光电转换效率达到23.12%，是MAPbI3中最高的效率之一。这项工作揭示了微观晶体结构对太阳能电池性能的影响。相关研究成果以“Tuning Lattice Structure of Ferroelastic Twin-Domains Achieving Efficient Perovskite Solar Cells”为题，于近日发表在ACS Energy Letters上。
该工作的共同第一作者是我组的Wajid Ali和秦炜，以上工作得到大连化物所创新基金、国家自然科学基金委“人工光合成”基础科学中心的资助。（文/图 秦炜, Wajid Ali）
文中相关文献链接地址：
Nature Commun., 2023: https://www.nature.com/articles/s41467-023-35837-1
