Ultrafast And Scalable Laser-Induced Crystallization Of Titanium Dioxide Films For Planar Perovskite Solar Cells

A conventional annealing method to fabricate metal oxide films used for perovskite solar cells (PSCs) is a time-consuming batch process. Herein, a near-IR fiber laser process with a unique design of power ramping program and beam configuration is developed to achieve ultrafast and scalable processing of TiO2 films for PSCs. Highly crystalline anatase TiO2 films can be synthesized in only 18.5 s by the laser process with a peak annealing temperature up to 800-850 degrees C, compared with that of the furnace-annealing at 500 degrees C for 30 min and an overall processing time of 3 h. Then, a unique capability of using this laser process is presented to anneal stacked layers of substrates coated with the TiO2 films simultaneously, with a uniform annealing area up to 15.2 cm(2), thereby potentially achieving an in-line production rate of over 43 cm(2) min(-1) (1 cm(2) in approximate to 1.4 s). Planar PSCs fabricated under a high relative humidity of 60-70% based on the TiO2 films annealed under optimal laser conditions show enhanced photovoltaic performance than the furnace-annealed samples. This laser process potentially opens a new avenue for scalable annealing and rapid production of thin films.