Science News: 2021 Angew. Chem. Int. Ed., How Green Chemistry Synthetic Materials Maintain PSC High Efficiency and Reduce Costs

　　Angewandte Chemie (IF 15.336) published a study by Mohammad Khaja Nazeeruddin, Vytautas Getautis of EPFL and Vytautas Getautis of Kaunas University of Technology (KTU) in December 2021. Hybrid lead halide perovskite solar cells (PSCs) have become potential competitors of silicon-based solar cells, and their power conversion efficiency (PCE) has been greatly improved, approaching the breakthrough point of commercialization. Hole-transporting material (HTM)  is one of the quintessential components required for efficient and stable PSC devices. However, when HTMs are converted from the laboratory to manufacture on a large scale, their complex structures often create issues such as increased cost and harmful substances in the synthesis schemes. To massively scale PSCs through simple, cost-effective, and green chemical without sacrificing the efficiency, here we use cyclobutane-based hole-selective materials to reduce costs and adverse environmental impact.

　　The process reveals the effect of different side-arm fragments onto cyclobutane central core through the optical, electrochemical, photophysical and photovoltaic measurements. It was found that cyclobutane fragment increases the glass transition temperature of final HTMs, making it more amorphous and morphologically stable. Moreover, compared with spiro-OMeTAD, the cyclobutane-centered HTM has better hole-drift mobility values, up to the order of 10⁻⁴ cm² Vs⁻¹. Among them, V1366-based PSCs achieves a high efficiency of 21% and has excellent long-term stability. Importantly, the authors fabricated perovskite solar modules that exhibited a record efficiency over 19% with an active area of 30.24 cm². The results of this study cover the main requirements for the successful implementation of perovskite solar cell technology.