Additive-Assisted Defect Passivation for Minimization of Open-Circuit Voltage Loss and Improved Perovskite Solar Cell Performance

Abstract

Trap state formation in perovskite films during their preparation is a key limitation restricting the device performance and stability of perovskite solar cells. These trap states are generally present at the surface of perovskite films and on grain boundaries and work as charge recombination centers, thereby influencing the device performance. Hence, regulating these detrimental trap states that are susceptible to deformation is vital for improving the solar cell performance. Herein, a unique methodology of trap states passivation has been demonstrated using multiple carboxylic acid-functionalized small aromatic molecules. Three additives, viz., benzene carboxylic acid (BCA), benzene-1,3-dicarboxylic acid (BDCA), and benzene-1,3,5-tricarboxylic acid (BTCA), have been utilized as additives in the precursor solution that reduced trap states in the perovskite films. Perovskite films generated in the presence of these additives strongly influence the charge transfer dynamics and result in improved performance and stability of the devices by lowering the photogenerated charge recombination. BTCA-incorporated devices result in the highest power conversion efficiency (PCE) of 18.30% with a significant improvement in the open-circuit voltage (V oc) to 1075.9 mV (an enhancement of ≈80 mV) compared to the control device. Additionally, the devices also show enhanced thermal stability.

Efficient and stable perovskite solar cells using manganese-doped nickel oxide as the hole transport layer

“…4(a) and (b) , respectively. 53 The CPD is determined by the interaction force between sample surface and a Pt-coated conductive cantilever probe, which is defined as CPD = ( φ tip − φ sample )/− e and e is the electronic charge. 54 The CPD variation for the un-doped NiO x film was found to be unevenly distributed between 65.3 and 127.6 mV, whereas that for the 0.5 mol% Mn-doped NiO x film was homogeneously distributed between a smaller scale range of −24.4 and 15 mV.…”

Molecular design for perovskite solar cells

“…Secondly, the additive molecules can be molecularly engineered to alter the resulting halide perovskite crystal structures, morphologies, and roughness; this is often accompanied with the formation of intermediate compounds in the precursor solution 76‐78 . Many molecular additives compatible with the halide perovskites are available, including those based on small organic molecules, fullerene polymers, and organometallic halide salts, which significantly influence the perovskite morphology and crystallization kinetics 79‐83 . The following aspects have been pointed out to effectively design the molecular additives for perovskite solar cells from the molecular engineering point of view.…”

Multi-functional Strategy: Ammonium Citrate-Modified SnO2 ETL for Efficient and Stable Perovskite Solar Cells

“…The selection of TAC was based on the following facts: TAC was reported as a dispersing agent for raw TiO 2 powders in the process of preparing multiphase ceramics due to its ability to change the colloidal characteristics of metal oxide colloidal solutions and increase the repulsive force between particles . The TAC molecule with three carboxyl groups could obtain a more excellent performance compared with molecules with single or two carboxyl groups. , Small-size cations like NH 4 + , which is a component of TAC, can effectively restrain the hysteresis effect of the device . Like other materials used to passivate interface defects, − TAC also has functional groups containing lone pair electrons.…”

“…30 The TAC molecule with three carboxyl groups could obtain a more excellent performance compared with molecules with single or two carboxyl groups. 31,32 Small-size cations like NH 4 + , which is a component of TAC, can effectively restrain the hysteresis effect of the device. 33 Like other materials used to passivate interface defects, 34−37 TAC also has functional groups containing lone pair electrons.…”