Numerical Investigation of Photo-Generated Carrier Recombination Dynamics on the Device Characteristics for the Perovskite/Carbon Nitride Absorber-Layer Solar Cell

Abstract

The nitrogenated holey two-dimensional carbon nitride (C2N) has been efficaciously utilized in the fabrication of transistors, sensors, and batteries in recent years, but lacks application in the photovoltaic industry. The C2N possesses favorable optoelectronic properties. To investigate its potential feasibility for solar cells (as either an absorber layer/interface layer), we foremost detailed the numerical modeling of the double-absorber-layer–methyl ammonium lead iodide (CH3NH3PbI3) –carbon nitride (C2N) layer solar cell and subsequently provided in-depth insight into the active-layer-associated recombination losses limiting the efficiency (η) of the solar cell. Under the recombination kinetics phenomena, we explored the influence of radiative recombination, Auger recombination, Shockley Read Hall recombination, the energy distribution of defects, Band Tail recombination (Hoping Model), Gaussian distribution, and metastable defect states, including single-donor (0/+), single-acceptor (−/0), double-donor (0/+/2+), double-acceptor (2/−/0−), and the interface-layer defects on the output characteristics of the solar cell. Setting the defect (or trap) density to 1015cm−3 with a uniform energy distribution of defects for all layers, we achieved an η of 24.16%. A considerable enhancement in power-conversion efficiency ( η~27%) was perceived as we reduced the trap density to 1014cm−3 for the absorber layers. Furthermore, it was observed that, for the absorber layer with double-donor defect states, the active layer should be carefully synthesized to reduce crystal-order defects to keep the total defect density as low as 1017cm−3 to achieve efficient device characteristics.

Design Insights and Photovoltaic Performance Analysis of Non-Lead Inorganic RbSnX3 (X = I, Br, Cl) Perovskites through Coupled Density Functional Theory and SCAPS-1D Simulation Frameworks

“…The major recombination mechanisms in the semiconductor materials are radiative, Auger, and band-to-band recombination in the bulk layer. The following equations describe radiative recombination ( R rad ) and Auger recombination ( R Aug ) R rad = B false( n p − n i 2 false) R Aug = C n false( n 2 p − n i 2 n false) + C p false( n 2 p − n i 2 p false) where B is the radiative recombination coefficient and C n defines the Auger electron/hole capture coefficient.…”

“…R Aug recombination occurs when a free electron and a hole combine, and the excess energy resulting from this recombination is promptly transferred to another carrier. This extra carrier gets enough energy to jump from a lower energy level to a higher energy level. , For the examination of R Aug , we have varied C n / C p from 10 –23 to 10 –29 cm 6 /s, as shown in Figure a,b. Note that V OC decreases from 0.88 to 0.73 V and from 1.07 to 0.96 V for RbSnBr 3 and RbSnCl 3 as the C n / C p factor increases, respectively.…”

“…The following equations describe radiative recombination (R rad ) and Auger recombination (R Aug ). 87 = R B np n ( )…”

“…This extra carrier gets enough energy to jump from a lower energy level to a higher energy level. 87,88 For the examination of R Aug , we have varied C n /C p from 10 −23 to 10 −29 cm 6 /s, as shown in Figure 21a,b. Note that V OC decreases from 0.88 to 0.73 V and from 1.07 to 0.96 V for RbSnBr 3 and RbSnCl 3 as the C n /C p factor increases, respectively.…”