Guangliang Li,Lingxian Kong,Qi Su,Xianhua Tan,Xuning Zhang,Zhiyong Liu,Tielin Shi,Guanglan Liao,Bo Sun
Few-layer black phosphorus (FL-BP) shows great potential in infrared polarization-sensitive photodetection due to its narrow bandgap and strong in-plane anisotropy. However, FL-BP is easy to be oxidized and degraded, which severely restricts its applications. Herein, a simple and scalable in situ interfacial passivation method based on pentacene film is reported to enhance the ambient stability of FL-BP as well as achieve n-type doping for improved polarization-sensitive photoimaging. High crystal quality FL-BP flakes with intrinsic anisotropy are prepared by electrochemical exfoliation. The morphology and Raman spectra of FL-BP/pentacene exhibit excellent stability 28 days after passivation. In addition, the hole mobility is significantly enhanced and dark current is substantially suppressed due to the interfacial passivation and n-type doping effect. The FL-BP/Pentacene based photodetector shows a broadband response from visible to near-infrared with good stability. The photoresponsivity under 915 nm illumination is calculated as 2.2 mA W −1 with an anisotropy ratio of 1.29. Furthermore, the polarization imaging under the irradiation at zigzag and armchair directions directly reveals the strong infrared polarization-sensitive imaging capability of FL-BP/pentacene. This work also opens up new avenues to enhance the photoresponse and stability of various optoelectronics based on similarly unstable 2D materials.
Li Ji,Xiang Peng,Tan Xinyu,Li Bowen,Zhang Kai,Zhu Ying,Ren Yanqi,Chen Xiaobo
Organic–inorganic lead halide peroxides (OIHPs) have attracted much interest due to their excellent photovoltaic properties, but practical applications are limited by long-term stability and further performance enhancement. Two-dimensional/three-dimensional (2D/3D) heterojunction is a promising strategy to address these issues. Here, short-chain 3,5-dichlorobenzylamine (DBA) with halogen functional groups is introduced to react with excess PbI 2 to form the 2D perovskite layer in mixed perovskite films of Cs 0.05 (FA 0.85 MA 0.15 ) 0.95 Pb(I 0.85 Br 0.15 ) 3 , which passivates surface defects, favours energy band alignment of functional layers and suppresses non-radiative recombination of carriers. As a result, DBA-treated 2D/3D PSCs obtained a champion PCE of 21.54% with an improved open circuit voltage ( V oc ) of 1.171 V. More importantly, the 2D/3D heterojunction can effectively protect the underlying 3D perovskite from moisture ingress. The unencapsulated 2D/3D devices retain 90% of their initial efficiency even after aging at 40 ± 5% RH for 1000 h, while the 3D device retains only 40%.
Rong Li,Jiale Ding,Xijiao Mu,Yifei Kang,Anran Wang,Weihui Bi,Yunhe Zhang,Jing Cao,Qingfeng Dong
The extreme instability of pure α-phase FAPbI 3 under high humidity conditions restricts the high-throughput fabrication in unmodified air environments, resulting in poor performance of α-phase FAPbI 3 perovskite devices obtained by scalable fabrication methods. Here we synthesized hyperbranched copper phthalocyanine (HCuPc) as a supramolecular additive with twisted phthalocyanine units to realize the molecular-level encapsulation at the grain boundaries through supramolecular interaction, which greatly broadened the processing window of FAPbI 3 under high humidity. At the same time, unlike traditional encapsulation layer that carrier can only be collected by tunneling effect, the twisted phthalocyanine ring of HCuPc in perovskite films is more conducive to hole extraction. Finally, a record efficiency was achieved in pure FAPbI 3 based inverted structured solar cell by blade-coating to the best of our knowledge, even under unmodified humid air conditions (relative humidity of 65%–85%). The best operational stability of 3D pure FAPbI 3 devices can also be achieved at the same time and unencapsulated HCuPc-FAPbI 3 device can even operate with negligible degradation for 100 h in the open air (RH 30%–40%).
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