Boosted hole extraction in all-inorganic CsPbBr3 perovskite solar cells by interface engineering using MoO2/N-doped carbon nanospheres composite.

Carbon-based all-inorganic CsPbBr 3 perovskite solar cells (PSCs) have been a promising candidate in the field of photovoltaics due to its simple preparation process and excellent stability in air with high humidity. However, the power conversion efficiency (PCE) of such cells is still unsatisfactory to this day because of the large energy offset and poor hole extraction at the interface of CsPbBr 3 /carbon. Here, a MoO 2 /N-doped carbon nanospheres (NC) composite with high hole mobility and matched energy level is prepared by a facile one-step pyrolysis process and introduced into carbon-based all-inorganic CsPbBr 3 PSC as a hole-transporting material (HTM) to enhance energy level alignment, interface contact and charge extraction as well as to passivate CsPbBr 3 surface defects, realizing the reduction of energy loss and charge recombination. The optimal PSC based on MoO 2 /NC composite without encapsulation achieves a maximum PCE as high as 9.40% in comparison with 6.68% efficiency for the reference device and exhibits an outstanding long-term stability over 800 h in air atmosphere with 80% relative humidity. This work provides an effective approach to build high-performance and stable all-inorganic CsPbBr 3 PSCs by introducing simple synthetic and efficient MoO 2 /NC composite inorganic HTM. Through enhancing energy level alignment and charge extraction as well as reducing surface defects, MoO 2 /N-doped carbon nanospheres composite HTMs help CsPbBr 3 PSC achieve a champion PCE of 9.40% and excellent stability. Image 1 • MoO 2 /NC composite is prepared by a facile one-step pyrolysis process. • The charge extraction at CsPbBr 3 /carbon interface is markedly promoted. • A maximum PCE as high as 9.40% is achieved for device based on MoO 2 /NC composite. • The unencapsulated device shows excellent long-term moisture tolerance over 800 h. [ABSTRACT FROM AUTHOR]