Optimization of titanium‐doped indium oxide anodes for heterojunction organic solar cells

We investigated the characteristics of Ti‐doped In2O3 (TIO) films grown by a direct current (DC) sputtering to use as a transparent anode for heterojunction organic solar cells (OSCs). The electrical, optical, structural, and morphological properties of the TIO films were comprehensively investigated as a function of Ti composition in TIO targets and TIO film thickness. The in‐situ substrate heating during DC sputtering led to an effective activation of Ti dopants and crystallization of the TIO films. At optimized conditions, the TIO film showed a low resistivity of 2.4 × 10−4 Ω cm and high optical transmittance of 80% comparable to crystalline ITO films. In particular, the TIO films showed a high near infrared transparency due to effect of the Ti dopant with high Lewis acid strength (3.06). The heterojunction OSCs fabricated on TIO anode exhibited a good cell‐performance with a fill factor of 62.53%, a short circuit current of 8.785 mA cm−2, an open circuit voltage of 0.607 V, and a power conversion efficiency of 3.333%, which are comparable to OSCs with ITO anodes (PCE 3.382).