{'fraction_non_alphanumeric': 0.03089143865842895, 'fraction_numerical': 0.02206531332744925, 'mean_word_length': 5.230769230769231, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Engineering diketopyrrolopyrrole sensitizers for highly efficient dye-sensitized solar cells: enhanced light harvesting and intramolecular charge transfer

Two asymmetric DPP dyes with a D–π–A structure are reported, where DPP is used as a bridge to connect the triphenylamine donor and cyanoacetic acid acceptor. The compact dyes exhibit high light absorption ability covering the whole visible spectral region. The most efficient cell exhibited a short-circuit current density of 17.72 mA cm−2, an open-circuit voltage of 725 mV, and a fill factor of 74%, yielding a power conversion efficiency of 9.51% under standard test conditions (irradiation of 1000 W m−2, air mass = 1.5 G), which is the highest value reported for DPP-based DSCs employing an I−/I3− redox couple. Furthermore, the DPP dyes show remarkable stability under long-term irradiation over 1000 h. Considering the facile synthesis and excellent stability, the DPP sensitizer would be a promising option for highly efficient DSCs. The results show that judicious molecular engineering is crucial for constructing highly efficient charge transfer sensitizers in DSCs.