Solution-processed amorphous p-type Cu-Sn-I thin films for transparent Cu-Sn-I/IGZO p–n junctions.

P-type Cu-Sn-I thin films with different Sn contents (CSn) were fabricated in air via a simple and low-cost spin-coating method. Sn additive facilitates the amorphization of CuI, and a complete amorphous phase of Cu-Sn-I film is achieved at CSn =15%. With increasing CSn, the optical bandgap increases and refractive index decreases, probably due to the influence of Sn-additive on both the electronic structure and phase state of the films. The air-processed Sn-free CuI films show p-type conduction with hole mobility and a concentration of 17.3 cm2/V−1 s−1 and 1.1 × 1019 cm−3, and an increasing trend of resistivity is observed along with a large drop in hole concentration during the Sn-inspired amorphization process. Moreover, transparent Cu-Sn-I/IGZO p–n junctions were constructed, exhibiting the optimum rectifying characteristic at CSn = 15% with a forward-to-reverse ratio of 6.2 × 103. [ABSTRACT FROM AUTHOR]