Low‐Cost Perovskite Solar Cells Employing Dimethoxydiphenylamine‐Substituted Bistricyclic Aromatic Enes as Hole Transport Materials

• Published in: ChemSusChem 2017-10, Vol.10 (19), p.3825-3832
• Main Authors: Rakstys, Kasparas, Paek, Sanghyun, Grancini, Giulia, Gao, Peng, Jankauskas, Vygintas, Asiri, Abdullah M., Nazeeruddin, Mohammad Khaja
• Format: Article
• Language: English
• Subjects: Amines - chemistry; bistricyclic aromatic ene; Calcium Compounds - chemistry; Chemical synthesis; Costs and Cost Analysis; Electric Power Supplies - economics; Electrochemistry; Energy conversion efficiency; hole transport material; Hydrocarbons, Aromatic - chemistry; Models, Molecular; Molecular Conformation; Oxides - chemistry; perovskite solar cells; Photovoltaic cells; photovoltaics; Reagents; Solar cells; Solar Energy; Titanium - chemistry; Transport
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201700974

The synthesis, characterization and photovoltaic performance of series of novel molecular hole transport materials (HTMs) based on bistricyclic aromatic enes (BAEs) are presented. The new derivatives were obtained following a simple and straightforward procedure from inexpensive starting reagents mimicking the synthetically challenging 9,9′‐spirobifluorene moiety of the well‐studied spiro‐OMeTAD. The novel HTMs were tested in mixed cations and anions perovskite solar cells (PSCs) yielding a power conversion efficiency (PCE) of 19.2 % under standard global 100 mW cm−2 AM1.5G illumination using 9‐{2,7‐bis[bis(4‐methoxyphenyl)amino]‐9H‐fluoren‐9‐ylidene}‐N2,N2,N7,N7‐tetrakis(4‐methoxyphenyl)‐9H‐thioxanthene‐2,7‐diamine (coded as KR374). The power conversion efficiency data confirms the easily attainable heteromerous fluorenylidenethioxanthene structure as valuable core for low‐cost and highly efficient HTM design and paves the way towards cost‐effective PSC technology. Bridge to success: We report the synthesis of three new hole transport materials (HTMs) using a cost‐effective procedure and the impact of different atoms in heteromerous bistricyclic aromatic ene scaffolds. S‐bridged KR374 shows a a significantly improved hole‐drift mobility leading to enhanced photovoltaic performance in mixed‐ion perovskite solar cells and reduced hysteresis owing to the improved interface between the perovskite and HTM caused by stronger Pb–S interaction.