Nanobowl arrays endow perovskite solar cells with iridescent colors

With the maturing of perovskite solar cells (PSCs) technology, it is highly desirable to develop colorful solar cells to satisfy the requirements of aesthetic purposes in applications including building integrated photovoltaics and wearable electronics. The broad optical absorption and the large absorption coefficient of perovskites normally lead to high-efficiency cells with dark-brown colors. Till now, two representative approaches have been used to achieve colorful PSCs: bandgap engineering and structural colors. The former approach usually leads to considerably reduced power conversion efficiency (PCE) values (typically less than 13%) owing to diminished optical absorption associated with the enlarged bandgap. The latter approach takes advantage of engineered optical properties arising from patterned structures, enabling the generation of structural colors that are bright and dazzling. Despite the great efforts devoted to the colorful PSCs with respectable efficiencies, it remains a challenge to realize high-efficiency, colorful PSCs through deliberate structural design.